Red Hat Linux Security Advisories & CVEs
12893 advisories tracked · Red Hat Security Data API · direct feeds checked every minute; rate-limited backstops use a safe source cadence
Android app · Google Play
Monitor Red Hat CVEs from your phone.
Choose a whole vendor or a precise platform, then receive matching security advisories by phone notification, email, or both. Coverage follows 34 official vendor sources and 160+ reviewed platform categories.
Security advisories for your Red Hat release
Pick your distribution release to see every advisory issued for it and its severity mix. Fixes ship as errata — keep the system patched. This is the release's advisory history, not a per-package scan.
Official source
Red Hat Security Data API
Red Hat Enterprise Linux errata (RHSA) via the official Red Hat Security Data API — CVE severity, CVSS and affected packages. A credential-free official source.
Latest Red Hat advisories
High [CVE-2026-74447] fix uint32_t overflow in EOP ring buffer size alignment
In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: fix uint32_t overflow in EOP ring buffer size alignment eop_ring_buffer_size in struct queue_properties is a u32. In kfd_queue_acquire_buffers() the expected EOP buffer size is computed as ALIGN(eop_ring_buffer_size, PAGE_SIZE); ALIGN uses typeof(x), so the addition is done in 32-bit. A user-supplied size of 0xFFFFF001 wraps to 0, causing kfd_queue_buffer_get() to skip its exact-size check (gated on size!= 0) and accept any BO mapped at the address. On GFX8/GFX9 the MQD cp_hqd_eop_control is then programmed for an 8KB EOP ring backed by a 4KB BO, so CP EOP writes can land past the buffer and fault the GPU. Cast the operand to u64 so the alignment is computed in 64-bit; the size check in kfd_queue_buffer_get() then rejects the oversized request. (cherry picked from commit ae443117b742c357bfef3a7bddabf76fcf86e9ef) An integer overflow vulnerability exists when aligning the End-of-Pipe (EOP) ring buffer size. A local attacker could exploit this by providing a specially crafted size that, due to a 32-bit integer overflow, causes the system to bypass buffer size checks. This could lead to writes beyond the intended buffer, potentially causing a Graphics Processing Unit (GPU) fault and resulting in a Denial of Service (DoS).
High [CVE-2026-74443] bound DMA command body size against suffix pointer
In the Linux kernel, the following vulnerability has been resolved: drm/vmwgfx: bound DMA command body size against suffix pointer vmw_cmd_dma() locates the DMA suffix at (unsigned long) &cmd->body + header->size - sizeof(*suffix) without checking that header->size is large enough to contain both cmd->body and the suffix. An undersized header makes the suffix pointer underflow back into the previous command in the bounce buffer. The verifier later writes suffix->maximumOffset, clobbering verified fields of an already-relocated earlier command -- a TOCTOU on the device-visible command stream that lets one command rewrite another's GMR id, surface id, or other authenticated fields. Reject the command if the body is too small for the suffix to fit. A local attacker could exploit a vulnerability in the `vmw_cmd_dma()` function, where an undersized header in a Direct Memory Access (DMA) command body causes a pointer to underflow. This allows the attacker to overwrite authenticated fields of a previously processed command. Such manipulation of the command stream could lead to privilege escalation or information disclosure. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-124.
High [CVE-2026-74441] Fix race condition and ordering in port unregistration
In the Linux kernel, the following vulnerability has been resolved: usb: typec: ucsi: Fix race condition and ordering in port unregistration A synchronization issue exists during port unregistration where pending partner work items can race against workqueue destruction, leading to use-after-free conditions: cros_ec_ucsi cros_ec_ucsi.3.auto: error -ETIMEDOUT: PPM init failed BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:__queue_work+0x83/0x4a0 Call Trace: __cfi_delayed_work_timer_fn+0x10/0x10 run_timer_softirq+0x3b6/0xbd0 sched_clock_cpu+0xc/0x110 irq_exit_rcu+0x18d/0x330 fred_sysvec_apic_timer_interrupt+0x5e/0x80 Fix this by ensuring strict ordering and proper serialization during teardown: 1. Move ucsi_unregister_partner() to the beginning of the teardown sequence and protect it under the connector mutex lock. 2. Ensure all pending partner tasks are explicitly flushed and finished before the workqueue is destroyed. 3. Switch from mod_delayed_work() to a cancel_delayed_work() and queue_delayed_work() sequence. Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
High [CVE-2026-74568] Fix race between LPI release and re-registration
In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: vgic: Fix race between LPI release and re-registration Fix a potential race between decrementing an LPI's reference count and evicting that structure from the LPI xarray. LPI structures are maintained in the VGIC LPI xarray (dist->lpi_xa). When the reference count of an LPI structure drops to zero, vgic_release_lpi_locked() removes the structure from the xarray and frees it under the xarray lock. However, the release of an LPI can race with a concurrent LPI re-registration with the same INTID via vgic_add_lpi() on another CPU, since the reference count drop and the xarray eviction are not performed in a single atomic step. This can happen e.g. if the guest issues a DISCARD while the LPI is still referenced from a vCPU's active-pending list (ap_list), and the same INTID is re-mapped via MAPTI. Particularly, vgic_release_lpi_locked() is called from two distinct paths: direct release via vgic_put_irq(), and deferred release via vgic_release_deleted_lpis(). Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
High [CVE-2026-74537] hold sk properly in iso_conn_ready
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: hold sk properly in iso_conn_ready sk deref in iso_conn_ready must be done either under conn->lock, or holding a refcount, to avoid concurrent close. conn->sk is currently accessed without either: [Task 1] [Task 2] iso_sock_release iso_conn_ready sk = conn->sk lock_sock(sk) conn->sk = NULL lock_sock(sk) release_sock(sk) iso_sock_kill(sk) UAF on sk deref Fix possible UAF by holding sk refcount in iso_conn_ready(). Also recheck after lock_sock that the socket is still valid. Adjust locking so conn->sk is cleared only under lock_sock. A race condition in the `iso_conn_ready` function allows a socket to be prematurely freed while still in use. This Use-After-Free (UAF) vulnerability could lead to memory corruption, potentially causing a system crash or other unpredictable behavior. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-825. 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-rt.
High [CVE-2026-74474] use pskb_network_may_pull for transmit path header pulls
In the Linux kernel, the following vulnerability has been resolved: vxlan: use pskb_network_may_pull() for transmit path header pulls In vxlan_xmit(), arp_reduce(), and vxlan_mdb_entry_skb_get(), pskb_may_pull() was being called to verify the availability of network layer headers (ARP, IPv6/ND, IP/IPv6 MDB keys). However, during transmit skb->data points to the MAC header, so skb_network_offset(skb) is ETH_HLEN (14 bytes). Using pskb_may_pull(skb, len) only checks len bytes from skb->data rather than skb_network_offset(skb) + len, which can leave part of the network header in non-linear frags. Replace these remaining pskb_may_pull() calls with pskb_network_may_pull() to properly account for the MAC header offset. This vulnerability arises from the incorrect handling of network packet headers during data transmission. Specifically, certain functions within the vxlan module fail to properly account for the initial part of the network packet, known as the Media Access Control (MAC) header. This oversight can lead to fragmented network header information, potentially causing unexpected network behavior or data processing errors. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-805. 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.
High [CVE-2026-74502] fix double free of out_cvts on rawmidi error
In the Linux kernel, the following vulnerability has been resolved: ALSA: ump: fix double free of out_cvts on rawmidi error snd_ump_attach_legacy_rawmidi() allocates the legacy conversion array ump->out_cvts and, on the snd_rawmidi_new() error path, frees it with kfree() but leaves ump->out_cvts pointing at the freed memory. When the endpoint is later torn down, snd_ump_endpoint_free() frees ump->out_cvts a second time, resulting in a double free. The host snd-usb-audio driver attaches the legacy rawmidi for any USB MIDI 2.0 (UMP) device, so a device that makes snd_rawmidi_new() fail reaches this path on enumeration. Clear ump->out_cvts after freeing it on the error path so it is not freed again during teardown. Discovered by XBOW, triaged by Baul Lee A flaw was found in the Linux kernel's Advanced Linux Sound Architecture (ALSA) Universal MIDI Packet (UMP) driver. This vulnerability, a double free error, occurs when handling legacy raw MIDI (Musical Instrument Digital Interface) conversions. Specifically, an error during the initialization of a USB MIDI 2.0 device can cause memory to be freed twice. This can lead to memory corruption or a system crash, resulting in a Denial of Service (DoS). Red Hat severity: Important — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-1341.
High [CVE-2026-74517] Cancel delayed I/O APIC EOI handling before destroying vCPUs
In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Cancel delayed I/O APIC EOI handling before destroying vCPUs Cancel (and flush) the I/O APIC's delayed EOI handling work during the "pre VM destroy" phase, before vCPUs are destroyed, as processing the EOI broadcast will inject another IRQ if the line is asserted, i.e. will try to deliver an IRQ to the target vCPU(s). Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
High [CVE-2026-74554] fix out-of-bounds clear_bit in ath12k_mac_dp_peer_cleanup
In the Linux kernel, the following vulnerability has been resolved: wifi: ath12k: fix out-of-bounds clear_bit in ath12k_mac_dp_peer_cleanup() ath12k_mac_dp_peer_cleanup() clears the ML peer ID slot on the free_ml_peer_id_map bitmap by indexing it with dp_peer->peer_id. That is wrong: dp_peer->peer_id for an MLO peer always carries the ATH12K_PEER_ML_ID_VALID bit (BIT(13)), so clear_bit() is invoked with index >= 0x2000, which is far outside the bitmap of ATH12K_MAX_MLO_PEERS (256) bits and corrupts memory adjacent to ah->free_ml_peer_id_map. The intended bitmap entry also never gets cleared, so subsequent ath12k_peer_ml_alloc() calls eventually run out of IDs. The ID without the VALID bit is what ath12k_peer_ml_alloc() returned and is stored in ahsta->ml_peer_id. Use that instead. While there, also reset ahsta->ml_peer_id to ATH12K_MLO_PEER_ID_INVALID so the bitmap and ahsta->ml_peer_id stay in sync. Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.115823.3 An out-of-bounds write vulnerability exists in the `ath12k_mac_dp_peer_cleanup()` function. This issue occurs due to incorrect indexing of a bitmap, leading to memory corruption adjacent to the bitmap. This could allow a malicious Wi-Fi peer to cause a denial of service or potentially achieve arbitrary code execution.
High [CVE-2026-74496] Fix use-after-free in fou_create
In the Linux kernel, the following vulnerability has been resolved: fou: Fix use-after-free in fou_create() fou_create() publishes struct fou through sk_user_data before adding the new FOU port to the per-netns list. If fou_add_to_port_list() fails, the error path frees fou while it is still reachable through sk_user_data. A concurrent receive can then dereference the freed object in fou_from_sock(). This ordering issue was previously noted in the linked discussion. The failure is reachable when local port 0 is requested. Each socket binds to a different ephemeral port, but fou_cfg_cmp() compares the requested port 0 and reports -EALREADY once an entry already exists. Release the tunnel socket before freeing fou so sk_user_data is cleared first, and defer reclamation with kfree_rcu() to protect concurrent RCU readers. This matches the lifetime handling in fou_release(). A flaw was found in the Linux kernel's Foo Over UDP (FOU) tunnel driver. An ordering issue in the `fou_create()` function can lead to a use-after-free vulnerability. This occurs when a `struct fou` object is published before being fully added to the system's list. If the addition fails, the object can be freed while still accessible, allowing a concurrent operation to access the freed memory. This could result in memory corruption and potentially lead to system instability or a denial of service.
High [CVE-2026-74575] Prevent XDomain delayed work use-after-free on disconnect
In the Linux kernel, the following vulnerability has been resolved: thunderbolt: Prevent XDomain delayed work use-after-free on disconnect tb_xdp_handle_request() runs on system_wq and queues xd->state_work via queue_delayed_work() in three request handlers: PROPERTIES_CHANGED_REQUEST, UUID_REQUEST (via start_handshake), and LINK_STATE_CHANGE_REQUEST. Similarly, update_xdomain() queues xd->properties_changed_work when local properties change. Concurrently, tb_xdomain_remove() calls stop_handshake() which does cancel_delayed_work_sync() on both delayed works. Later, tb_xdomain_unregister() calls device_unregister() which eventually frees the xdomain. Since commit 559c1e1e0134 ("thunderbolt: Run tb_xdp_handle_request() in system workqueue") moved the request handler off tb->wq, the handler and the remove path are no longer serialized. If queue_delayed_work() executes after cancel_delayed_work_sync() but before the xdomain is freed, the delayed work fires on a freed object. Add xd->removing that tb_xdomain_remove() sets under xd->lock before calling stop_handshake(). Each external queue site holds the same lock and checks removing before calling queue_delayed_work(). Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
High [CVE-2026-74516] Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active
In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: Update x2APIC MSR intercepts if AVIC is inhibited while L2 is active Always update x2APIC MSR intercepts for L1 when AVIC is deactivated, even if L2 is active and KVM is using a separate MSR bitmap to run L2. If AVIC is fully enabled prior to running L2, and is then inhibited while L2 is active (for a VM-scoped inhibit), then KVM will run L1 with AVIC disabled, but with x2APIC MSR intercepts disabled, i.e. will allow L1 to read most of the host's APIC state, send arbitrary interrupts, change task priority, and ultimately trivially DoS the host. E.g. sending a self-IPI in L1 on HYPERV_REENLIGHTENMENT_VECTOR, 0xee, with CONFIG_HYPERV=n in the host kernel as a "safe" PoC, yields: Spurious interrupt (vector 0xee) on CPU#425. Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
High [CVE-2026-74534] fix refcounting of iso_conn
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: fix refcounting of iso_conn iso_conn_del() and iso_chan_del() have a race that results to double-put of iso_conn: [Task hdev->workqueue] [Task 2] iso_conn_del iso_chan_del iso_conn_hold_unless_zero iso_conn_lock iso_conn_lock conn->sk = NULL iso_conn_unlock sk = iso_sock_hold(conn) conn own refcount when non-NULL, so iso_conn_del does not need to put it. A race condition between `iso_conn_del()` and `iso_chan_del()` functions can lead to a double-put of `iso_conn` objects. This can result in a Use-After-Free (UAF) vulnerability, potentially allowing an attacker to cause a denial of service or achieve arbitrary code execution. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-825. 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-rt.
High [CVE-2026-74518] fix list corruption in allocate_file_region_entries
In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix list corruption in allocate_file_region_entries() allocate_file_region_entries() tops up resv->region_cache with freshly allocated file_region descriptors. The allocation uses GFP_KERNEL, so resv->lock is dropped around it: the new entries are gathered on a stack-local list head, allocated_regions, and spliced into resv->region_cache once the lock is re-acquired. The splice used list_splice(), which moves the entries but does not re-initialize the source head, so allocated_regions is left pointing at an entry that now lives on resv->region_cache. The top-up runs in a while loop that re-checks the cache deficit after re-acquiring the lock. For a shared mapping the resv_map is shared by every mapper of the hugetlbfs inode, so a concurrent region_chg()/region_add()/region_del() on the same resv_map can consume cache entries during the unlocked window and force a second iteration. Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
High [CVE-2026-74556] Bound SCSI Response data segment to the connection buffer
In the Linux kernel, the following vulnerability has been resolved: scsi: libiscsi_tcp: Bound SCSI Response data segment to the connection buffer iscsi_tcp_hdr_dissect() receives the data segment of several PDU types into the fixed-size conn->data buffer, which is allocated for ISCSI_DEF_MAX_RECV_SEG_LEN (8192) bytes. For the LOGIN_RSP, TEXT_RSP, REJECT and ASYNC_EVENT opcodes the dissect path already rejects a PDU whose DataSegmentLength exceeds that buffer. The SCSI Command Response (ISCSI_OP_SCSI_CMD_RSP) path also copies its data segment (sense/response data) into conn->data via iscsi_tcp_data_recv_prep(), but it does so without the same check. The only upstream bound on in.datalen is conn->max_recv_dlength, the initiator's advertised MaxRecvDataSegmentLength, which is commonly negotiated well above 8192 (open-iscsi defaults to 262144). A target that returns a SCSI Response with a DataSegmentLength between 8193 and max_recv_dlength therefore overflows the 8192-byte conn->data buffer. Once the same bound applies, ISCSI_OP_SCSI_CMD_RSP is handled exactly like those responses: bound the data segment, receive it into conn->data when present, and otherwise complete the PDU with no data. Fold the opcode into that case group rather than duplicating the check.
Medium [CVE-2026-72428] Fix stack slot index in nospec checks
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix stack slot index in nospec checks check_stack_write_fixed_off() computes the byte slot for a fixed-offset stack write as -off - 1, and records each written byte in slot_type[] with (slot - i) % BPF_REG_SIZE. The Spectre v4 sanitization pre-check uses slot_type[i] instead. For a 4-byte write at fp-8 after the lower half of fp-8 has been zeroed, the pre-check scans bytes 0..3 and sees STACK_ZERO while the actual write updates bytes 7..4. That can leave the second half-slot write without nospec_result even though the bytes being overwritten still require sanitization. A flaw was found in the Berkeley Packet Filter (BPF) component of the Linux kernel. An incorrect calculation of the stack slot index during Spectre v4 sanitization checks could result in certain memory bytes not being properly sanitized. This vulnerability might allow an attacker to potentially disclose sensitive information through speculative execution side-channel attacks. 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-1285. 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-2026-72245] Fix device reference leak in host1x_device_parse_dt error path
In the Linux kernel, the following vulnerability has been resolved: gpu: host1x: Fix device reference leak in host1x_device_parse_dt() error path After device_initialize(), the embedded struct device in struct host1x_device should be released through the device core with put_device(). In host1x_device_add(), if host1x_device_parse_dt() fails, the current error path frees the object directly with kfree(device). That bypasses the normal device lifetime handling and leaks the reference held on the embedded struct device. The issue was identified by a static analysis tool I developed and confirmed by manual review. This oversight leads to a device reference leak, which could potentially result in resource exhaustion and a Denial of Service (DoS) over an extended period. 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-911. 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-rt.
Medium [CVE-2026-72403] Fix NULL pointer dereference in interface lookup
In the Linux kernel, the following vulnerability has been resolved: ALSA: FCP: Fix NULL pointer dereference in interface lookup A malformed USB device can provide a vendor-specific interface without any endpoint descriptors. fcp_find_fc_interface() currently selects the first vendor-specific interface and reads endpoint 0 from it, without checking whether the interface actually has any endpoints. When bNumEndpoints is zero, no endpoint array is allocated for the parsed alternate setting, so get_endpoint(..., 0) yields an invalid endpoint descriptor pointer. Dereferencing it through usb_endpoint_num() then triggers a NULL pointer dereference. Skip vendor-specific interfaces that do not have any endpoints. A flaw was found in the ALSA FireWire Control Protocol (FCP) component of the Linux kernel. A local attacker with a specially crafted USB device could trigger a NULL pointer dereference. This occurs because the `fcp_find_fc_interface()` function attempts to access an endpoint descriptor from a malformed USB device that does not provide any, leading to an invalid pointer dereference. This vulnerability could cause a system crash, resulting in a Denial of Service (DoS). 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-476. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9.
Medium [CVE-2026-72190] fix mrec_lock ABBA deadlock in rename
In the Linux kernel, the following vulnerability has been resolved: ntfs: fix mrec_lock ABBA deadlock in rename ntfs_file_fsync(), ntfs_dir_fsync() and __ntfs_write_inode() lock an inode's mrec_lock before taking the mrec_lock of its parent directory. ntfs_rename() takes old_ni->mrec_lock and old_dir_ni->mrec_lock before taking new_ni->mrec_lock for an existing target, or new_dir_ni->mrec_lock for a cross-directory rename. A flaw was found in the Linux kernel's NTFS filesystem driver. An incorrect locking order (ABBA deadlock) during file rename operations can lead to a race condition. A local attacker could exploit this by performing specific file system operations, causing the system to deadlock. This results in a Denial of Service (DoS), making the system unresponsive. 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-833. 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-2026-72292] Initialize KVM_S390_GET_CMMA_BITS memory
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Initialize KVM_S390_GET_CMMA_BITS memory kvm_s390_get_cmma_bits() allocates its output buffer with vmalloc(), which does not zero the returned pages: values = vmalloc(args->count); In the non-peek (migration) path, dat_get_cmma() reports a byte count spanning from the first to the last dirty page, but __dat_get_cmma_pte() writes values[gfn - start] only for pages whose CMMA dirty bit is set. The walk uses DAT_WALK_IGN_HOLES, so clean and unmapped pages that lie between two dirty pages within the reported span are visited but never store their byte. Those gaps (up to KVM_S390_MAX_BIT_DISTANCE pages each) stay uninitialized yet fall inside [0, count) and are copied out by copy_to_user(), disclosing stale kernel memory to user space. Before the switch to the new gmap implementation the buffer was fully populated for every gfn in the span, so no uninitialized bytes were exposed; the dirty-only walk introduced the leak. Use vzalloc() so the gaps read back as zero. A local user could exploit a vulnerability in the KVM_S390_GET_CMMA_BITS ioctl, specifically within the `kvm_s390_get_cmma_bits()` function. This function allocates memory without properly initializing all pages, leading to uninitialized memory regions.