CVE-2026-56208

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Last Modified: UTC

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

Description

A heap buffer overflow vulnerability was found in libaom, the reference AV1 codec implementation. A flaw in the AV1 encoder's Look-Ahead Processing (LAP) mode causes the first-pass stats ring buffer wrap-around guard to be bypassed when g_lag_in_frames is set to 1 or higher. This results in a 232-byte out-of-bounds write on every encoded frame after the second, corrupting adjacent heap objects. An attacker who can influence encoder configuration in a transcoding service or WebRTC session could exploit this to cause a denial of service (process crash) or potentially achieve code execution.

Statement

This vulnerability is rated as Important severity because a heap buffer overflow with attacker-influenced data can cause reliable denial of service and potentially lead to code execution, though the attacker has only indirect control over the written values (encoder-computed statistics). In Red Hat products, libaom ships bundled within Firefox and Thunderbird as a statically-linked dependency used for AV1 decoding and WebRTC encoding. The vulnerable code path requires the encoder to be configured with g_lag_in_frames >= 1 (Look-Ahead Processing mode). In Firefox's WebRTC implementation, the encoder configuration is controlled by the browser itself and not exposed to remote peers, which significantly limits the attack surface compared to standalone transcoding services. RHEL-AI 3.4 and Hummingbird 1 ship standalone libaom (aom) packages at versions within the affected range. Applications on those platforms that use the libaom encoder API with LAP mode and accept untrusted configuration input are vulnerable.

Mitigation

There is no complete mitigation for this vulnerability. The following measures can reduce risk:

1. If using libaom as a standalone encoder library, avoid setting g_lag_in_frames to values >= 1 when processing untrusted input, or validate all encoder configuration parameters before passing them to the libaom API.
2. For Firefox and Thunderbird, ensure browsers are updated to versions that include the patched libaom (v3.14.0 or later).
3. For standalone libaom deployments (RHEL-AI, Hummingbird), restrict access to the encoding service to trusted clients only.
4. Apply network-level access controls to limit who can submit video for encoding.

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 Enterprise Linux 10.0 Extended Update Support firefox Fixed RHSA-2026:54181
Red Hat Enterprise Linux 7 Extended Lifecycle Support firefox Fixed RHSA-2026:54248
Red Hat Enterprise Linux 8 firefox Fixed RHSA-2026:47105
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support firefox Fixed RHSA-2026:54180
Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On firefox Fixed RHSA-2026:54180
Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support firefox Fixed RHSA-2026:54259
Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On firefox Fixed RHSA-2026:54259
Red Hat Enterprise Linux 8.8 Telecommunications Update Service firefox Fixed RHSA-2026:54339
Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions firefox Fixed RHSA-2026:54339
Red Hat Enterprise Linux 9 firefox Fixed RHSA-2026:47104

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 7.6 N/A 7.6
Attack Vector Network N/A Network
Attack Complexity Low N/A Low
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 Low N/A Low
Availability Impact High N/A High

CVSS v3 Vector

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

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