CVE-2026-56211 — Red Hat
HIGHCVE-2026-56211 is a high-severity (CVSS 7.1) Out-of-bounds Write vulnerability. No vendor fix is recorded yet; mitigation options are listed below.
A remote code execution vulnerability was found in libaom, the reference AV1 codec implementation. Insufficient bounds validation in the AV1 encoder's SVC (Scalable Video Coding) layer…
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-56211.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-56211 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 380,526 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Description
A remote code execution vulnerability was found in libaom, the reference AV1 codec implementation. Insufficient bounds validation in the AV1 encoder's SVC (Scalable Video Coding) layer ID control allows an attacker to supply crafted video frame pixels that overlap with internal encoder layer context structures. In fork-based video processing services, an attacker can use this to hijack the cyclic refresh map pointer, brute-force the process base address via a crash oracle, and redirect control flow to achieve arbitrary command execution. Exploitation requires the target service to use libaom with SVC encoding enabled and accept attacker-supplied video frames.
Detection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2026-56211 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated as Critical severity because the researcher demonstrated successful remote code execution against a fork-based video processing service. The exploit chain leverages attacker-controlled pixel values to hijack internal encoder pointers, uses a crash oracle to brute-force ASLR, and ultimately…
There is no complete mitigation for this vulnerability. The following measures can reduce risk: 1. If using libaom as a standalone encoder in a fork-based service, validate all SVC layer parameters (spatial_layer_id, temporal_layer_id) against configured bounds before passing them to the encoder API. 2. Avoid fork-based architectures for encoding services that accept untrusted input. Use thread-based or container-isolated workers instead, which prevent crash oracle attacks. 3. Restrict access to encoding services to trusted clients only. Do not expose SVC encoder configuration or frame submission to untrusted network input. 4. For Firefox and Thunderbird, ensure browsers are updated to…Source: Red Hat security advisory for CVE-2026-56211 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux AI 3.3 for RHEL 9 | aom-0:3.14.0-1.el9ai | RHSA-2026:51100 |
| Red Hat Enterprise Linux AI 3.4 for RHEL 9 | aom-0:3.14.0-1.el9ai | RHSA-2026:51146 |
| Red Hat Enterprise Linux AI 3.5 for RHEL 9 | aom-0:3.14.0-1.el9ai | RHSA-2026:42875 |
| Red Hat AI Inference Server 3.2 | rhaiis/vllm-cuda-rhel9:1787860580 | RHSA-2026:61627 |
| Red Hat AI Inference Server 3.2 | rhaiis/model-opt-cuda-rhel9:1787772157 | RHSA-2026:61628 |
| Red Hat AI Inference Server 3.2 | rhaiis/vllm-rocm-rhel9:1787884873 | RHSA-2026:61629 |
| Red Hat AI Inference Server 3.3 | rhaiis/model-opt-cuda-rhel9:1789508287 | RHSA-2026:68696 |
| Red Hat AI Inference Server 3.3 | rhaiis/vllm-spyre-rhel9:1789502493 | RHSA-2026:68697 |
Frequently Asked Questions
Is CVE-2026-56211 in your dependencies?
Find it across , including transitive dependencies.