CVE-2026-56211

Summary

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.

Affected Software

VendorProductVersion RangeStatus
Red HatRed Hat Hardened Images3.14.0-0.1.hum1 < *unaffected

Weaknesses

  • CWE-787: Out-of-bounds Write

Workarounds

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.

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: total

libaom: libaom: remote code execution via SVC layer context handling with attacker-controlled frames

Additional References

References