# CVE-2026-125191: FFmpeg through 9.0.2 V4L2 M2M Decoder Deadlock via Reference Count Leak

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

FFmpeg through 9.0.2 contains a reference count leak in libavcodec/v4l2_buffers.c that allows attackers to deadlock the V4L2 mem2mem decoder on multi-plane capture formats. Attackers can supply crafted H.264, HEVC, or VP9 streams with resolution changes, making ff_v4l2_m2m_codec_reinit() wait forever and hang the decoding application.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/FFmpeg/FFmpeg/commit/4d2d58efa9b9f3802893b1db0ea1edfbe1cc66ef

## Affected products and versions

- FFmpeg / FFmpeg (ffmpeg/ffmpeg): ≥ 0; ≤ 9.0.2 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.7 (medium); CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 4.7 (medium); CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:N/I:N/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-911

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25682 (CNA: VulnCheck; issue-tracking)

- https://github.com/FFmpeg/FFmpeg/commit/4d2d58efa9b9f3802893b1db0ea1edfbe1cc66ef (CNA: VulnCheck; patch)

- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/v4l2_buffers.c#L274 (CNA: VulnCheck; technical-description)

- https://github.com/FFmpeg/FFmpeg (CNA: VulnCheck; product)

- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-v4l2-m2m-decoder-deadlock-via-reference-count-leak (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-125191; retrieved 2026-11-09; source updated 2026-11-09

Revision: 8e655d901ecd473874ad64dcbe03a0dca4e24082db11ff0306585d8d32cd3460

Canonical: https://y2.dev/cve/CVE-2026-125191

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