What is CVE-2026-125205?

CVE-2026-125205 is a medium-severity vulnerability in Ffmpeg, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.5/10. Published 2026-11-09.

How severe is CVE-2026-125205?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Resource exhaustion in Ffmpeg

CVE-2026-125205

FFmpeg through 9.0.2 contains an unbounded memory allocation vulnerability in the av1_frame_merge bitstream filter that allows attackers to exhaust memory by never sending a temporal delimiter OBU. Attackers can supply a crafted .obu file opened by the AV1 OBU or Annex B demuxers, forcing unlimited OBU buffering per temporal unit and causing denial of service.

Published 2026-11-09.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Ffmpeg

Weakness classification (CWE)

CWE-770 — Allocation of Resources Without Limits or Throttling

References

code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25569 (issue-tracking)
github.com/FFmpeg/FFmpeg (product)
github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/bsf/av1_frame_merge.c (technical-description)
Patch Commit (patch)
VulnCheck Advisory: FFmpeg through 9.0.2 Memory Exhaustion via av1_frame_merge Bitstream Filter (third-party-advisory)

Frequently asked questions

What is CVE-2026-125205?: CVE-2026-125205 is a medium-severity vulnerability in Ffmpeg, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.5/10. Published 2026-11-09.
How severe is CVE-2026-125205?: Medium severity. CVSS v3 base score is 5.5 out of 10.