Medium [CVE-2026-12892] 1-byte heap out-of-bounds read in H.264 NAL extension slice parser
This medium-severity Red Hat Linux advisory covers CVE-2026-12892 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 7.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
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.
Is CVE-2026-12892 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-12892 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-12892?
The advisory VulniPulse tracks names no fixed release. Follow Red Hat's guidance for workarounds and updates.
Confirm against the vendor advisory before you patch.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
Mitigation checklist
- No mitigation is currently available that meets Red Hat Product Security's standards for usability, deployment, applicability, or stability.
Official advisory · high-confidence parse· fetched 14 days ago·verify at source
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