CVE-2026-56211

Public on

Last Modified: UTC

Important Important severity What does this mean?
7.1 CVSS v3 Score Breakdown

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.

Statement

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 achieves arbitrary command execution. However, the attack complexity is elevated: it requires a fork-based service architecture (for the crash oracle), multiple encoding attempts (for ASLR brute-force), and knowledge of the target binary layout. In Red Hat products, libaom ships bundled within Firefox and Thunderbird. Firefox does not use a fork-based architecture for WebRTC encoding, and SVC layer parameters are managed internally, making the demonstrated exploit chain not directly applicable to the browser context. RHEL-AI 3.4 (aom 3.12.0) and Hummingbird 1 (aom 3.13.3) ship standalone libaom packages within the affected version range. Fork-based transcoding or video conferencing services that use libaom with SVC encoding and accept attacker-supplied frames are at highest risk for this specific exploit chain.

Mitigation

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 versions that include the patched libaom (v3.14.0 or later).
5. Enable all available exploit mitigations (ASLR, PIE, stack canaries, CFI) on encoding service binaries.

Additional information

External References

Affected Packages and Issued Red Hat Security Errata

Unless explicitly stated as not affected, all previous versions of packages in any minor update stream of a product listed here should be assumed vulnerable, although may not have been subject to full analysis.

Products / Services Components State Errata
Red Hat AI Inference Server 3.2 rhaiis/vllm-cuda-rhel9 Fixed RHSA-2026:61627
Red Hat AI Inference Server 3.2 rhaiis/model-opt-cuda-rhel9 Fixed RHSA-2026:61628
Red Hat AI Inference Server 3.2 rhaiis/vllm-rocm-rhel9 Fixed RHSA-2026:61629
Red Hat Enterprise Linux AI 3.3 for RHEL 9 aom Fixed RHSA-2026:51100
Red Hat Enterprise Linux AI 3.4 for RHEL 9 aom Fixed RHSA-2026:51146
Red Hat Enterprise Linux AI 3.5 for RHEL 9 aom Fixed RHSA-2026:42875
Red Hat Hardened Images aom-main Fixed RHSA-2026:30814
Red Hat OpenShift AI 3.4 rhoai/odh-mlserver-rhel9 Fixed This content is not included.RHSA-2026:60520
Red Hat OpenShift AI 3.4 rhoai/odh-th06-cpu-torch210-py312-rhel9 Fixed This content is not included.RHSA-2026:60520
Red Hat OpenShift AI 3.4 rhoai/odh-th06-cuda130-torch210-py312-rhel9 Fixed This content is not included.RHSA-2026:60520

Common Vulnerability Scoring System (CVSS) Score Details

Important note

CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authorities (CNA) source for its products and services (see Red Hat classifications ).

CVSS v3 Score Breakdown

Red Hat NVD cve.org
CVSS v3 Base Score 7.1 N/A 7.1
Attack Vector Network N/A Network
Attack Complexity High N/A High
Privileges Required None N/A None
User Interaction Required N/A Required
Scope Unchanged N/A Unchanged
Confidentiality Impact Low N/A Low
Integrity Impact High N/A High
Availability Impact High N/A High

CVSS v3 Vector

Red Hat CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:H

cve.org CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:H

Acknowledgements

Red Hat would like to thank The FuzzAnything Team (FuzzAnything) for reporting this issue.

Frequently Asked Questions

Why is Red Hat's CVSS v3 score or Impact different from other vendors?

 For open source software shipped by multiple vendors, the CVSS base scores may vary for each vendor's version depending on the version they ship, how they ship it, the platform, and even how the software is compiled. This makes scoring of vulnerabilities difficult for third-party vulnerability databases such as NVD that only provide a single CVSS base score for each vulnerability. Red Hat scores reflect how a vulnerability affects our products specifically.

For more information, see https://access.redhat.com/solutions/762393.

My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
  • "Under investigation" doesn't necessarily mean that the product is affected by this vulnerability. It only means that our Analysis Team is still working on determining whether the product is affected and how it is affected.
  • "Affected" means that our Analysis Team has determined that this product is affected by this vulnerability and might release a fix to address this in the near future.

What can I do if my product is listed as "Will not fix"?

 A "will not fix" status means that a fix for an affected product version is not planned or not possible due to complexity, which may create additional risk.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Upgrade to a supported product version that includes a fix for this vulnerability (recommended).
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.

What can I do if my product is listed as "Fix deferred"?

 A deferred status means that a fix for an affected product version is not guaranteed due to higher-priority development work.

Available options depend mostly on the Impact of the vulnerability and the current Life Cycle phase of your product. Overall, you have the following options:
  • Apply a mitigation (if one exists).
  • Open a This content is not included.support case to request a prioritization of releasing a fix for this vulnerability.
  • Red Hat Engineering focuses on addressing high-priority issues based on their complexity or limited lifecycle support. Therefore, lower-priority issues will not receive immediate fixes.

What is a mitigation?

 A mitigation is an action that can be taken to reduce the impact of a security vulnerability, without deploying any fixes.

I have a Red Hat product but it is not in the above list, is it affected?

 The listed products were found to include one or more of the components that this vulnerability affects. These products underwent a thorough evaluation to determine their affectedness by this vulnerability. Note that layered products (such as container-based offerings) that consume affected components from any of the products listed in this table may be affected and are not represented.

Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?

 In order to maintain code stability and compatibility, Red Hat usually does not rebase packages to entirely new versions. Instead, we backport fixes and new features to an older version of the package we distribute. This can result in some security scanners that only consider the package version to report the package as vulnerable. To avoid this, we suggest that you use an approved vulnerability scanner from our This content is not included.Red Hat Vulnerability Scanner Certification program.

My product is listed as "Out of Support Scope". What does this mean?

 When a product is listed as "Out of Support Scope", it means a vulnerability with the impact level assigned to this CVE is no longer covered by its current support lifecycle phase. The product has been identified to contain the impacted component, but analysis to determine whether it is affected or not by this vulnerability was not performed. The product should be assumed to be affected. Customers are advised to apply any mitigation options documented on this page, consider removing or disabling the impacted component, or upgrade to a supported version of the product that has an update available.