Red Hat Linux Security Advisories & CVEs
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Latest Red Hat advisories
Medium [CVE-2026-6653] Denial of Service via crafted XML input due to use-after-free
Use After Free in libxml2's xmlParseInternalSubset from GNOME libxml2 version 2.9.11 to 2.11.0 allows a remote attacker to cause a denial-of-service via maliciously crafted XML input with improper entity resolution handling. A flaw was found in libxml2. This improper handling of entity resolution can lead to a denial-of-service (DoS), making the affected system or application unavailable. This Moderate impact use-after-free vulnerability in libxml2 can lead to a denial of service in Red Hat products that process untrusted XML input. In the worst-case scenario, a remote attacker is able to provide specially crafted XML, which, if parsed by an affected application, could cause the application to crash. Red Hat severity: Moderate — CVSS 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-416. Affected Red Hat products: Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Discovery 2; Red Hat Update Infrastructure 5; Red Hat OpenShift Container Platform 4. Red Hat lists Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Hardened Images as not affected. Red Hat fixing advisory: RHSA-2026:69655, RHSA-2026:61247, RHSA-2026:61783, RHSA-2026:66018. Affected products named by the advisory: Red Hat package: libxml2.
Medium [CVE-2026-12892] 1-byte heap out-of-bounds read in H.264 NAL extension slice parser
A flaw was found in GStreamer's gst-plugins-bad package. When processing a specially crafted H.264 video file containing malformed MVC or SVC extension slice NAL units, a 1-byte heap out-of-bounds read can occur during parsing. This happens when the parser attempts to check slice boundary information without first verifying that the NAL unit contains enough data beyond the extension header. An attacker could exploit this by tricking a user into opening a malicious H.264 video file, potentially causing the application to crash or leak a single byte of heap memory. Red Hat product impact analysis pending. Component mapping required to determine which products ship the affected code. The vulnerable code path specifically affects H.264 NAL extension slices (type 20) used in MVC (Multi-view Video Coding) and SVC (Scalable Video Coding) formats, which are less commonly encountered than baseline H.264. The out-of-bounds read is limited to 1 byte and requires local file access with user interaction (opening a crafted video file). Modern Linux distributions include ASLR and stack canaries which provide some defense-in-depth against heap-based vulnerabilities, though these do not prevent the initial out-of-bounds read from occurring. Red Hat severity: Moderate — CVSS 4.4 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:L). Weakness: CWE-125.
Medium [CVE-2026-52910] Free reuseport cBPF prog after RCU grace period.
In the Linux kernel, the following vulnerability has been resolved: bpf: Free reuseport cBPF prog after RCU grace period. Eulgyu Kim reported the splat below with a repro. [0] The repro sets up a UDP reuseport group with a cBPF prog and replaces it with a new one while another thread is sending a UDP packet to the group. The reuseport prog is freed by sk_reuseport_prog_free(). bpf_prog_put() is called for "e"BPF prog to destruct through multiple stages while cBPF prog is freed immediately by bpf_release_orig_filter() and bpf_prog_free(). If a reuseport prog is detached from the setsockopt() path (reuseport_attach_prog() or reuseport_detach_prog()), sk_reuseport_prog_free() is called without waiting for RCU readers to complete, resulting in various bugs. Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; and 1 more.
Medium [CVE-2026-56132] Arbitrary Code Execution via Heap-based Buffer Overflow
In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers. A flaw was found in libexpat, a library used for parsing XML data. An attacker could exploit a heap-based buffer overflow, a type of memory error, by providing specially crafted XML input. This vulnerability occurs when the library mishandles memory reallocation while processing XML, particularly when multiple parsers share data. Successful exploitation could allow the attacker to execute arbitrary code, access sensitive information, or cause the application to crash, leading to a denial of service. Red Hat severity: Moderate — CVSS 6.9 (CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L). Weakness: CWE-131. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; Red Hat Hardened Images; Red Hat Update Infrastructure 5; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat OpenShift Container Platform 4. Will not fix / out of support: Red Hat Enterprise Linux 6. Red Hat fixing advisory: RHSA-2026:64810, RHSA-2026:64809, RHSA-2026:64812, RHSA-2026:30647, RHSA-2026:67956.
Medium [CVE-2025-15661] Information disclosure and denial of service via crafted SFTP response
libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation. This can disclose heap memory contents or crash the application, causing a denial of service (DoS). Red Hat severity: Moderate — CVSS 6.5 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H). Weakness: CWE-125. Affected Red Hat products: Red Hat Hardened Images; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7. Will not fix / out of support: Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7. Red Hat fixing advisory: RHSA-2026:30132. Affected products named by the advisory: Red Hat package: libssh2.
Medium [CVE-2026-48990] Resource exhaustion via oversized JSON Web Signature (JWS) payloads
joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions 1.3.4 through 1.6.5, joserfc accepts oversized RFC7797 b64=false JWS payloads without applying JWSRegistry.max_payload_length, which can lead to resource exhaustion. The normal JWS compact and flattened JSON paths reject payloads above the configured payload-size limit with ExceededSizeError. The RFC7797 unencoded payload paths do not make the same check. A valid b64=false compact or flattened JSON JWS can therefore deserialize successfully with a payload larger than JWSRegistry.max_payload_length. Applications that accept lower-trust JWS values and rely on joserfc to reject oversized token content during verification have a moderate availability risk. This issue has been fixed in version 1.6.7. This vulnerability allows a remote attacker to cause resource exhaustion, leading to a Denial of Service (DoS), by sending oversized JSON Web Signature (JWS) payloads. The library fails to apply size limits, specifically JWSRegistry.max_payload_length, when processing RFC7797 b64=false JWS payloads. Red Hat severity: Moderate — CVSS 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L). Weakness: CWE-770.
Medium [CVE-2026-55199] Denial of Service via crafted SSH_MSG_EXT_INFO message
libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops. A vulnerability in libssh2 allows a malicious SSH server to freeze connected clients during the handshake process. By triggering an infinite CPU loop during the initial connection handshake, the server can render the client unresponsive. Note: Red Hat Enterprise Linux (RHEL) 8 and newer are not affected by this flaw, as they do not ship the libssh2 package. Red Hat severity: Moderate — CVSS 5.9 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H). Weakness: CWE-606. Affected Red Hat products: Red Hat Hardened Images; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7. Will not fix / out of support: Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7. Red Hat fixing advisory: RHSA-2026:29950. Affected products named by the advisory: Red Hat package: libssh2.
Medium [CVE-2026-9678] Information disclosure due to improper cache-control header parsing
Impact: Undici's cache interceptor incorrectly classifies some responses as cacheable when the upstream Cache-Control header uses whitespace-padded qualified private or no-cache field names such as private=" authorization" or no-cache="\tauthorization". The parser preserves the surrounding whitespace, so later comparisons against the literal authorization field name fail and the response is stored. In shared-cache mode, this allows a response containing one user's authenticated data to be served from cache to a subsequent caller, including an unauthenticated caller, when both requests resolve to the same cache key. Affected applications are those that explicitly enable the cache interceptor (interceptors.cache()) in shared mode, forward Authorization headers upstream, and receive cacheable responses with non-canonical qualified private or no-cache directives. Patches: Upgrade to undici v7.28.0 or v8.5.0. Workarounds: If upgrade is not immediately possible, disable shared-cache mode for traffic that includes Authorization headers, avoid caching responses to authenticated requests, or add Vary: Authorization upstream. A flaw was found in Undici. This vulnerability allows an unauthenticated attacker to access authenticated user data from the cache, leading to information disclosure.
Medium [CVE-2026-9675] undici WebSocket client vulnerable to denial of service via cumulative fragment bypass
Impact: The undici WebSocket client enforces maxPayloadSize per-frame but does not enforce the cumulative size of fragmented uncompressed messages. A malicious WebSocket server can stream many small fragments that each pass per-frame validation but collectively exceed the configured limit, causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service. Affected applications are those using the undici WebSocket client (new WebSocket(...)) that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint. This is a regression specific to undici 8.1.0. The 6.25.0 line shipped the equivalent cumulative check from the start and is unaffected. The 7.x line never had the maxPayloadSize feature and is also unaffected. Patches: Upgrade to undici >= 8.5.0. Workarounds: No workaround is available. The fix must be applied through an upgrade. A flaw was found in undici. A malicious WebSocket server could exploit this vulnerability by sending fragmented messages that individually meet size limits but collectively exceed them. This is rated Moderate by Red Hat (CVSS 5.9) because successful exploitation requires the undici WebSocket client to connect to an attacker-controlled server (AC:H), which is unlikely in typical Red Hat product deployments where WebSocket endpoints are trusted internal services.
Medium [CVE-2026-12515] missing repository authorization in content_uploads exposes cross-product content existence
A flaw was found in Katello's of Red Hat Satellite. A content upload functionality where insufficient authorization checks in the ContentUploadsController allowed users with the edit_products permission to query content information for repositories outside the products they were authorized to manage. An authenticated attacker could exploit this issue to determine whether specific content exists within repositories that should otherwise be inaccessible. This issue does not allow unauthorized modification, import, or publication of content. Affected products named by the advisory: Red Hat Satellite 6.16 for RHEL 8; Red Hat Satellite 6.16 for RHEL 9; Red Hat Satellite 6.17 for RHEL 9; Red Hat Satellite 6.18 for RHEL 9; and 2 more. Affected products named by the advisory: Red Hat Satellite 6.19 for RHEL 9.
Medium [CVE-2026-48142] Memory disclosure or denial of service via ngx_http_charset_module heap buffer over-read
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When content is served or proxied through a location block with both source_charset utf-8; and a charset directive (for example, charset koi8-r;) configured, remote, unauthenticated attackers can send requests (in conjunction with conditions beyond their control) to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. A flaw was found in NGINX. Remote, unauthenticated attackers can exploit a vulnerability in the `ngx_http_charset_module` when specific charset configurations are present. Red Hat severity: Moderate — CVSS 4.8 (CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L). Weakness: CWE-125. Affected Red Hat products: Red Hat Hardened Images; Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9. Red Hat fixing advisory: RHSA-2026:27197. Affected products named by the advisory: Red Hat package: nginx.
Medium [CVE-2026-2604] Evolution-data-server: evolution data server: arbitrary file deletion via inconsistent uri handling
A flaw was found in evolution-data-server. Inconsistent comparison logic in the addressbook file backend allows a Flatpak application with D-Bus access to craft a malicious URI containing directory traversal sequences. This URI is stored without proper validation during contact creation or modification. Later, during contact deletion, the URI is processed with a less strict check, leading to the deletion of arbitrary files on the host filesystem. This could potentially include critical Flatpak override files. Red Hat severity: Moderate — CVSS 5.6 (CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:L). Weakness: CWE-73. 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. Red Hat does not currently list a fixing RHSA for this CVE. Affected products named by the advisory: Red Hat package: evolution-data-server.
Medium [CVE-2026-12330] Incorrect boundary conditions in the Internationalization component
Incorrect boundary conditions in the Internationalization component. This vulnerability was fixed in Firefox ESR 140.12, Firefox ESR 115.37, and Thunderbird 140.12. Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory. Red Hat severity: Moderate — CVSS 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N). Weakness: CWE-131. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 7 Extended Lifecycle Support; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On; Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On; Red Hat Enterprise Linux 8.8 Telecommunications Update Service; Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.6 Extended Update Support; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7. Will not fix / out of support: Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7.
Medium [CVE-2026-12327] Memory safety bugs fixed in Firefox ESR 140.12, Thunderbird ESR 140.12, Firefox 152 and Thunderbird 152
Memory safety bugs present in Firefox ESR 140.11, Thunderbird ESR 140.11, Firefox 151 and Thunderbird 151. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory. Red Hat severity: Moderate — CVSS 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N). Weakness: CWE-787. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 10.0 Extended Update Support; Red Hat Enterprise Linux 7 Extended Lifecycle Support; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On; Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support; Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On; Red Hat Enterprise Linux 8.8 Telecommunications Update Service; Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions; Red Hat Enterprise Linux 9.6 Extended Update Support; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7.
Medium [CVE-2026-12315] Mitigation bypass in the DOM: Security component
Mitigation bypass in the DOM: Security component. Red Hat rates this moderate (CVSS 6.1). Weakness: CWE-807. Affected package(s): firefox, thunderbird. Resolved in Red Hat advisory RHSA-2026:29940 — update the affected packages (`sudo dnf update`). Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 1.
Medium [CVE-2026-12314] Memory safety bug fixed in Thunderbird ESR 140.12
Memory safety bug fixed in Thunderbird ESR 140.12. Red Hat rates this moderate (CVSS 6.1). Weakness: CWE-787. Affected package(s): firefox, thunderbird. Resolved in Red Hat advisory RHSA-2026:29940 — update the affected packages (`sudo dnf update`). Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 1.
Medium [CVE-2026-12313] Information disclosure, sandbox escape in the Security: Process Sandboxing component
Information disclosure, sandbox escape in the Security: Process Sandboxing component. Red Hat rates this moderate (CVSS 6.1). Weakness: CWE-403. Affected package(s): firefox, thunderbird. Resolved in Red Hat advisory RHSA-2026:29940 — update the affected packages (`sudo dnf update`). Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 1.
Medium [CVE-2026-12311] Information disclosure, sandbox escape in the Security: Process Sandboxing component
Information disclosure, sandbox escape in the Security: Process Sandboxing component. Red Hat rates this moderate (CVSS 6.1). Weakness: CWE-243. Affected package(s): firefox, thunderbird. Resolved in Red Hat advisory RHSA-2026:29940 — update the affected packages (`sudo dnf update`). Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 1.
Medium [CVE-2026-12310] Memory safety bug fixed in Thunderbird ESR 140.12
Memory safety bug fixed in Thunderbird ESR 140.12. Red Hat rates this moderate (CVSS 6.1). Weakness: CWE-825. Affected package(s): firefox, thunderbird. Resolved in Red Hat advisory RHSA-2026:29940 — update the affected packages (`sudo dnf update`). Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 1.
Medium [CVE-2026-12308] Memory safety bug fixed in Thunderbird ESR 140.12
Memory safety bug fixed in Thunderbird ESR 140.12. Red Hat rates this moderate (CVSS 6.1). Affected package(s): firefox, thunderbird. Resolved in Red Hat advisory RHSA-2026:29940 — update the affected packages (`sudo dnf update`). Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 1.