CVE-2026-56209

CVE-2026-56209 is a high-severity vulnerability with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

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.

Frequently asked questions

What is CVE-2026-56209?
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.
How severe is CVE-2026-56209?
CVE-2026-56209 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2026-56209 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-56209?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-56209 have an EU (EUVD) identifier?
Yes. CVE-2026-56209 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-38044.
When was CVE-2026-56209 published?
CVE-2026-56209 was published on 2026-06-19 and last updated on 2026-07-08.

References

Other CWE-787 (Out-of-bounds Write) vulnerabilities

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