Red Hat Linux Security Advisories & CVEs
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Latest Red Hat advisories
Medium [CVE-2026-64116] add NULL check for idev in ipv6_hop_ioam
In the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: add NULL check for idev in ipv6_hop_ioam() Reported by Sashiko: The function ipv6_hop_ioam() accesses __in6_dev_get(skb->dev)->cnf.ioam6_enabled without validating the returned idev pointer. Because addrconf_ifdown() can concurrently clear dev->ip6_ptr via RCU, __in6_dev_get() can return NULL during interface teardown, which could cause a NULL pointer dereference when processing an IOAM Hop-by-Hop option. Let's add a check and use SKB_DROP_REASON_IPV6DISABLED accordingly. A flaw was found in the Linux kernel's IPv6 In-situ Operations, Administration, and Maintenance (IOAM) module. This vulnerability allows a remote attacker to cause a system crash, leading to a Denial of Service (DoS). The flaw occurs because the `ipv6_hop_ioam()` function does not properly validate a pointer during IPv6 interface teardown, which can result in a NULL pointer dereference when processing an IOAM Hop-by-Hop option. This vulnerability is rated as Moderate severity because successful exploitation leads to a kernel crash and denial of service without exposing sensitive data or enabling code execution, but it depends on hitting a narrow race condition during network interface teardown. Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat package: kernel.
Medium [CVE-2026-64127] send packed pdu, not stack pointer
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: ecred_reconfigure: send packed pdu, not stack pointer Commit 1c08108f3014 ("Bluetooth: L2CAP: Avoid -Wflex-array-member-not-at-end warnings") converted the on-stack request PDU in l2cap_ecred_reconfigure() from an explicit packed struct to DEFINE_RAW_FLEX(), but did not adjust the size and source-pointer arguments to l2cap_send_cmd(): - struct { - struct l2cap_ecred_reconf_req req; - __le16 scid; - } pdu; + DEFINE_RAW_FLEX(struct l2cap_ecred_reconf_req, pdu, scid, 1);... l2cap_send_cmd(conn, chan->ident, L2CAP_ECRED_RECONF_REQ, sizeof(pdu), &pdu); After the conversion, DEFINE_RAW_FLEX() expands to declare an anonymous union pdu_u plus a local pointer "pdu" pointing at it. Therefore: - sizeof(pdu) is now sizeof(struct l2cap_ecred_reconf_req *) = 8 on 64-bit (4 on 32-bit), not the 6 bytes of (mtu, mps, scid[1]). - &pdu is the address of the local pointer's stack storage, not the address of the request payload. l2cap_send_cmd() forwards (data, count) to l2cap_build_cmd(), which calls skb_put_data(skb, data, count). The L2CAP_ECRED_RECONFIGURE_REQ packet body therefore contains 8 bytes copied from the kernel stack starting at &pdu -- the 8 bytes overlap the pdu pointer's value, leaking a kernel stack address to the paired Bluetooth peer.
Medium [CVE-2026-64045] tcp - use cached peer pointer in ovpn_tcp_close
In the Linux kernel, the following vulnerability has been resolved: ovpn: tcp - use cached peer pointer in ovpn_tcp_close() ovpn_tcp_close() loads the ovpn_socket via rcu_dereference_sk_user_data() under rcu_read_lock(), takes a reference on sock->peer, caches the peer pointer in a local, and drops the read lock. It then passes sock->peer (rather than the cached local) to ovpn_peer_del(), re-dereferencing the ovpn_socket after the RCU read section has ended. Unlike ovpn_tcp_sendmsg(), which uses the same "load under RCU, use after unlock" pattern but is protected by lock_sock() held across the function, ovpn_tcp_close() runs without the socket lock: inet_release() invokes sk_prot->close() without taking lock_sock first. ovpn_socket_release() can therefore complete its kref_put -> detach -> synchronize_rcu -> kfree(sock) sequence concurrently, in the window after ovpn_tcp_close() drops rcu_read_lock() but before it dereferences sock->peer. The synchronize_rcu() in ovpn_socket_release() protects readers that use the dereferenced pointer inside the RCU read section, not those that escape the pointer to a local and use it afterwards. A reproducer follows the pattern of commit 94560267d6c4 ("ovpn: tcp - don't deref NULL sk_socket member after tcp_close()"): trigger a peer removal (keepalive expiration or netlink OVPN_CMD_DEL_PEER) at the same moment userspace closes the TCP fd.
Medium [CVE-2026-64183] Allocate runtime workqueue before ACPI init
In the Linux kernel, the following vulnerability has been resolved: efi: Allocate runtime workqueue before ACPI init Since commit 5894cf571e14 ("acpi/prmt: Use EFI runtime sandbox to invoke PRM handlers") ACPI PRM calls are delegated to a workqueue which runs in a kernel thread, making it easier to detect and mitigate faulting memory accesses performed by the firmware. Rafael reports that such PRM accesses may occur before efisubsys_init() executes, which is where the workqueue is allocated, leading to NULL pointer dereferences. Since acpi_init() [which triggers the early PRM accesses] executes as a subsys_initcall() as well, and has its own dependencies that may be sensitive to initcall ordering, deferring acpi_init() is not an option. So instead, split off the workqueue allocation into its own postcore initcall, as this is the only missing piece to allow EFI runtime calls to be made. This ensures that EFI runtime call (including PRM calls) are accessible to all code running at subsys_initcall() level. This vulnerability occurs due to a NULL pointer dereference when ACPI (Advanced Configuration and Power Interface) PRM (Platform Runtime Mechanism) calls are made before the necessary workqueue is allocated. This can lead to system instability or crashes, resulting in a denial of service. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
Medium [CVE-2026-64090] avoid empty VLAN responses
In the Linux kernel, the following vulnerability has been resolved: batman-adv: tt: avoid empty VLAN responses The commit 16116dac2339 ("batman-adv: prevent TT request storms by not sending inconsistent TT TLVLs") added checks to the local (direct) TT response code. But the response can also be done indirectly by another node using the global TT state. To avoid such inconsistency states reported in the original fix, also avoid sending empty VLANs for replies from the global TT state. A flaw was found in the Linux kernel's batman-adv (Better Approach To Mobile Ad-hoc Networking - Advanced) translation table module. This vulnerability could allow an attacker to cause network instability or a denial of service (DoS). The issue arises from the system sending inconsistent translation table type-length-value (TLVs) and empty VLAN responses, which can lead to 'TT request storms' within the network. The resolution prevents the sending of empty VLANs for replies, mitigating the risk of these inconsistencies. Red Hat severity: Moderate. Weakness: CWE-770. Red Hat lists Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9 as not affected.
Medium [CVE-2026-64077] move to two-stage removal scheme
In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: move to two-stage removal scheme Like previous patches for x_tables, follow same pattern in ebtables. We can't reuse xt helpers: ebt_table struct layout is incompatible. table->ops assignment is now done while still holding the ebt mutex to make sure we never expose partially-filled table struct. A concurrency issue exists during the two-stage removal scheme where the `table->ops` assignment could expose a partially-filled table structure if the `ebt` mutex is not held. This could lead to unpredictable system behavior. This vulnerability is rated as Moderate severity because exploitation is restricted to local attackers with privileges to configure bridge firewalling, and the primary impact is denial of service through kernel instability or crash rather than arbitrary code execution. The flaw stems from improper locking when unregistering Ethernet bridge filter tables, exposing incomplete data structures to concurrent operations. Because the underlying code sequence was introduced in newer kernel branches, older Red Hat Enterprise Linux releases are not affected, and typical enterprise deployments increasingly rely on nftables rather than legacy bridge filtering. Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-413.
Medium [CVE-2026-64072] fix bio leak on mapping failure
In the Linux kernel, the following vulnerability has been resolved: nvme: fix bio leak on mapping failure The local bio is always NULL, so we'd leak the bio if the integrity mapping failed. Just get it directly from the request. A flaw was found in the Linux kernel's Non-Volatile Memory Express (NVMe) subsystem. This vulnerability occurs when an integrity mapping fails, leading to a 'bio' (block I/O) leak. This resource leak can potentially lead to a denial of service (DoS) due to resource exhaustion. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-772. Affected Red Hat products: Red Hat Enterprise Linux 10. Red Hat does not currently list a fixing RHSA for this CVE. Affected products named by the advisory: Red Hat package: kernel.
Medium [CVE-2026-53370] Improve validation and configuration of ACR masks
In the Linux kernel, the following vulnerability has been resolved: perf/x86/intel: Improve validation and configuration of ACR masks Currently there are several issues on the user space ACR mask validation and configuration. - The validation for user space ACR mask (attr.config2) is incomplete, e.g., the ACR mask could include the index which belongs to another ACR events group, but it's not validated. - An early return on an invalid ACR mask caused all subsequent ACR groups to be skipped. - The stale hardware ACR mask (hw.config1) is not cleared before setting new hardware ACR mask. The following changes address all of the above issues. - Figure out the event index group of an ACR group. Any bits in the user-space mask not present in the index group are now dropped. - Instead of an early return on invalid bits, drop only the invalid portions and continue iterating through all ACR events to ensure full configuration. - Explicitly clear the stale hardware ACR mask for each event prior to writing the new configuration. Besides, a non-leader event member of ACR group could be disabled in theory. This could cause bit-shifting errors in the acr_mask of remaining group members. But since ACR sampling requires all events to be active, this should not be a big concern in real use case. Add a "FIXME" comment to notice this risk.
Medium [CVE-2026-53367] fix avdcache auditing
In the Linux kernel, the following vulnerability has been resolved: selinux: fix avdcache auditing The per-task avdcache was incorrectly saving and reusing the audited vector computed by avc_audit_required() rather than recomputing based on the currently requested permissions and distinguishing the denied versus allowed cases. As a result, some permission checks were not being audited, e.g. directory write checks after a previously cached directory search check. [PM: line wrap tweaks] This prevented some critical security permission checks, such as directory write operations, from being properly audited. As a result, an attacker could potentially perform actions without them being recorded in the system's audit logs, leading to a security bypass of auditing mechanisms. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-778. Affected Red Hat products: Red Hat Enterprise Linux 6. Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat does not currently list a fixing RHSA for this CVE. Affected products named by the advisory: Red Hat package: kernel.
Medium [CVE-2026-53372] Block PASID attachment to nested domain with dirty tracking
In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Block PASID attachment to nested domain with dirty tracking Kernel lacks dirty tracking support on nested domain attached to PASID, fails the attachment early if nesting parent domain is dirty tracking configured, otherwise dirty pages would be lost. A flaw was found in the Linux kernel's Input/Output Memory Management Unit (IOMMU) subsystem. This vulnerability arises in virtualized environments when a nested domain attempts to attach to a Process Address Space ID (PASID), a mechanism for devices to access memory, while its parent domain is configured for dirty page tracking. The kernel lacks proper dirty tracking support for the nested domain in this scenario, leading to a failure in attachment and the potential loss of dirty pages. This can result in data integrity issues or system instability within the virtualized environment. Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-820. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9. Red Hat does not currently list a fixing RHSA for this CVE. Affected products named by the advisory: Red Hat package: kernel.
Medium [CVE-2026-53369] reject descriptors with oversized CRC length
In the Linux kernel, the following vulnerability has been resolved: udf: reject descriptors with oversized CRC length udf_read_tagged() skips CRC verification when descCRCLength + sizeof(struct tag) exceeds the block size. A crafted UDF image can set descCRCLength to an oversized value to bypass CRC validation entirely; the descriptor is then accepted based solely on the 8-bit tag checksum, which is trivially recomputable. Reject such descriptors instead of silently accepting them. A legitimate single-block descriptor should never have a CRC length that exceeds the block. A flaw was found in the Linux kernel's Universal Disk Format (UDF) filesystem. A remote attacker could craft a malicious UDF image with an oversized Cyclic Redundancy Check (CRC) length. This could allow the attacker to bypass the integrity validation of UDF descriptors, leading to the acceptance of potentially corrupted or malicious data based on a weak checksum. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-354. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat does not currently list a fixing RHSA for this CVE.
Medium [CVE-2026-53371] bound node_desc sysfs read with %.64s
In the Linux kernel, the following vulnerability has been resolved: RDMA/ionic: bound node_desc sysfs read with %.64s node_desc[64] in struct ib_device is not guaranteed to be NUL- terminated. The core IB sysfs handler uses "%.64s" for exactly this reason (drivers/infiniband/core/sysfs.c:1307), since node_desc_store() performs a raw memcpy of up to IB_DEVICE_NODE_DESC_MAX bytes with no NUL termination: memcpy(desc.node_desc, buf, min_t(int, count, IB_DEVICE_NODE_DESC_MAX)); If exactly 64 bytes are written via the node_desc sysfs file, the array contains no NUL byte. The ionic hca_type_show() handler uses unbounded "%s" and will read past the end of node_desc into adjacent fields of struct ib_device until it encounters a NUL. ionic supports IB_DEVICE_MODIFY_NODE_DESC, so this is triggerable by userspace. Match the core handler and bound the format specifier. A flaw was found in the Linux kernel's ionic Remote Direct Memory Access (RDMA) driver. A local user can exploit this vulnerability due to an unbounded read operation when displaying the `node_desc` sysfs file. If the `node_desc` field is not null-terminated, the system will read beyond its allocated buffer, potentially exposing sensitive information from adjacent memory regions within the `ib_device` structure. Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-125.
Medium [CVE-2026-53373] do not try to unmap a VMA if mmap_prepare invoked from mmap
In the Linux kernel, the following vulnerability has been resolved: mm/vma: do not try to unmap a VMA if mmap_prepare() invoked from mmap() The mmap_prepare hook functionality includes the ability to invoke mmap_prepare() from the mmap() hook of existing 'stacked' drivers, that is ones which are capable of calling the mmap hooks of other drivers/file systems (e.g. overlayfs, shm). As part of the mmap_prepare action functionality, we deal with errors by unmapping the VMA should one arise. This works in the usual mmap_prepare case, as we invoke this action at the last moment, when the VMA is established in the maple tree. However, the mmap() hook passes a not-fully-established VMA pointer to the caller (which is the motivation behind the mmap_prepare() work), which is detached. So attempting to unmap a VMA in this state will be problematic, with the most obvious symptom being a warning in vma_mark_detached(), because the VMA is already detached. It's also unncessary - the mmap() handler will clean up the VMA on error. So to fix this issue, this patch propagates whether or not an mmap action is being completed via the compatibility layer or directly. If the former, then we do not attempt VMA cleanup, if the latter, then we do. This patch also updates the userland VMA tests to reflect the change. A flaw was found in the Linux kernel's memory management (mm/vma) component.
Medium [CVE-2026-53378] Fix blob property reference tracking in state lifecycle
In the Linux kernel, the following vulnerability has been resolved: drm/colorop: Fix blob property reference tracking in state lifecycle The colorop state blob property handling had memory leaks during state duplication, destruction, and reset operations. The implementation failed to follow the established pattern from drm_crtc's handling of DEGAMMA/GAMMA blob properties. Issues fixed: - drm_colorop_atomic_destroy_state() was freeing state memory without releasing the blob reference, causing a leak - drm_colorop_reset() was directly freeing old state with kfree() instead of properly destroying it, leaking blob references - drm_colorop_cleanup() had duplicate blob cleanup code Changes: - Add __drm_atomic_helper_colorop_destroy_state() helper to properly release blob references before freeing state memory - Update drm_colorop_atomic_destroy_state() to call the helper - Fix drm_colorop_reset() to use drm_colorop_atomic_destroy_state() for proper cleanup of old state - Simplify drm_colorop_cleanup() to use the common destruction path This matches the well-tested pattern used by drm_crtc since 2016 and ensures proper reference counting throughout the state lifecycle. Co-developed by Claude Sonnet 4.5. A flaw was found in the Linux kernel's Direct Rendering Manager (DRM) color operation module (drm/colorop).
Medium [CVE-2026-53379] free control handler on error in ov8856_init_controls
In the Linux kernel, the following vulnerability has been resolved: media: i2c: ov8856: free control handler on error in ov8856_init_controls() The control handler wasn't freed if adding controls failed, add an error exit label and convert the existing error return to use it. This vulnerability occurs due to improper error handling where a control handler is not correctly released if an error occurs during its initialization. This oversight could potentially lead to resource exhaustion, which may result in a denial of service (DoS) condition, making the system unavailable to legitimate users. Red Hat severity: Low — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-772. Affected Red Hat products: Red Hat Enterprise Linux 10. Red Hat does not currently list a fixing RHSA for this CVE. Affected products named by the advisory: Red Hat package: kernel.
Medium [CVE-2026-53376] Add upper bound check for num_of_nodes
In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: Add upper bound check for num_of_nodes drm/amdkfd: Add upper bound check for num_of_nodes in kfd_ioctl_get_process_apertures_new. (cherry picked from commit 98ff46a5ea090c14d2cdb4f5b993b05d74f3949f) A flaw was found in the AMD Kernel Fusion Driver (AMDKFD) in the Linux kernel. This vulnerability exists in the `kfd_ioctl_get_process_apertures_new` function, where a missing upper bound check for the `num_of_nodes` argument could allow a local attacker to provide an excessively large value. This could lead to an out-of-bounds read or write, potentially resulting in information disclosure or a denial of service to the system. This vulnerability is rated as Moderate severity for Red Hat Enterprise Linux because exploitation requires local unprivileged access to the AMD compute interface and affects only environments equipped with supported AMD GPU hardware. On systems running AMD graphics processing units, an authenticated user capable of issuing ioctls against the driver can trigger memory corruption through unbounded parameters, leading to a system crash or information leakage. Systems without AMD accelerators or environments where device nodes for GPU compute are restricted to privileged accounts remain unaffected. Weakness: CWE-125.
Medium [CVE-2026-53375] Prevent partial address patches
In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/vce: Prevent partial address patches In the case that only one of lo/hi is valid, the patching could result in a bad address written to in FW. A flaw was found in the Linux kernel, specifically within the drm/amdgpu/vce component responsible for video encoding. This vulnerability arises when the system attempts to update a memory address using incomplete information, where only a portion of the address is valid. This can result in data being written to an unintended memory location in the firmware, which could allow an attacker to execute unauthorized code or disrupt system operations. Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-787. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat does not currently list a fixing RHSA for this CVE. Affected products named by the advisory: Red Hat package: kernel-rt.
Medium [CVE-2026-53390] fix out-of-bounds read in smb_check_perm_dacl
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix out-of-bounds read in smb_check_perm_dacl() The permission-check ACE walk in smb_check_perm_dacl() validates the ACE header size and caps sid.num_subauth at SID_MAX_SUB_AUTHORITIES, but it never checks that ace->size is actually large enough to contain num_subauth sub-authorities before compare_sids() dereferences them. CIFS_SID_BASE_SIZE covers the SID header up to but excluding the sub_auth[] array, and offsetof(struct smb_ace, sid) is the ACE header, so the existing guards only guarantee the 8-byte SID base, i.e. zero sub-authorities. compare_sids() then reads ace->sid.sub_auth[i] for i num_subauth, ace->sid.num_subauth). The local comparison SIDs (sid_everyone, sid_unix_NFS_mode, and the id_to_sid() result) always have at least one sub-authority, and an attacker controls the ACE revision and authority bytes (which lie within the in-bounds SID base), so they can match one of those SIDs and force the sub_auth read. A crafted ACE with size == 16 and num_subauth >= 1 placed at the tail of the security descriptor therefore causes a heap out-of-bounds read of up to SID_MAX_SUB_AUTHORITIES * sizeof(__le32) bytes past the pntsd allocation.
Medium [CVE-2026-53400] fix adapter registration race
In the Linux kernel, the following vulnerability has been resolved: i2c: core: fix adapter registration race Adapters can be looked up based on their id using i2c_get_adapter() which takes a reference to the embedded struct device. Make sure that the adapter (including its struct device) has been initialised before adding it to the IDR to avoid accessing uninitialised data which could, for example, lead to NULL-pointer dereferences or use-after-free. Note that the i2c-dev chardev, which is registered from a bus notifier, currently uses i2c_get_adapter() so the adapter needs to be added to the IDR before registration. A flaw was found in the Linux kernel, specifically within its I2C (Inter-Integrated Circuit) core component. This vulnerability arises from a timing issue during the registration of I2C adapters, where an adapter could be accessed before it is fully prepared. This premature access to uninitialized data may lead to system instability, crashes, or a denial of service (DoS). Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-824. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Red Hat does not currently list a fixing RHSA for this CVE. Affected products named by the advisory: Red Hat package: kernel-rt.
Medium [CVE-2026-53385] fix null-ptr-deref in vcs_notifier during concurrent vcs_write
In the Linux kernel, the following vulnerability has been resolved: vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write A KASAN null-ptr-deref was observed in vcs_notifier(): BUG: KASAN: null-ptr-deref in vcs_notifier+0x98/0x130 Read of size 2 at addr qmp_cmd_name: qmp_capabilities, arguments: {} The issue is a race condition in vcs_write(). When the console_lock is temporarily dropped (to copy data from userspace), the vc_data pointer obtained from vcs_vc() may become stale. After re-acquiring the lock, vcs_vc() is called again to re-validate the pointer. If the vc has been deallocated in the meantime, vcs_vc() returns NULL, and the while loop breaks (with written > 0). However, after the loop, vcs_scr_updated(vc) is still called with the now-NULL vc pointer, leading to a null pointer dereference in the notifier chain (vcs_notifier dereferences param->vc). Fix this by adding a NULL check for vc before calling vcs_scr_updated(). A race condition in the `vcs_write()` function can lead to a null pointer dereference. This occurs when the `vc_data` pointer becomes stale during concurrent write operations, and a subsequent call attempts to use the now-invalid pointer. A local attacker could exploit this vulnerability to cause a system crash, resulting in a Denial of Service (DoS).
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