CVE-2026-56209: aom Out-of-bounds Write

Vulnerability summary

CVE-2026-56209 is a high (CVSS 7.1) Out-of-bounds Write vulnerability in aom. EPSS estimates a 0.64% chance of exploitation in the next 30 days, higher than 49.8% of scored vulnerabilities.

Timeline

1. 19-06-2026
   PublishedVulnerability first disclosed.
2. 19-10-2026
   Last modifiedVulnerability information updated.

Description

An arbitrary address write vulnerability was found in libaom, the reference AV1 codec implementation. A missing bounds check in the SVC (Scalable Video Coding) layer ID control function allows an attacker to inject an arbitrary pointer into the cyclic refresh map field via crafted image pixel values. The encoder then writes approximately 1,200 bytes at the attacker-controlled address. This is fully deterministic and does not require a separate information leak. An attacker who can supply frames to a network-facing libaom encoder with SVC enabled could exploit this for denial of service or potential code execution.

• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.