Quick answers
- Is CVE-2026-125253 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-125253 being exploited in the wild.
- How severe is CVE-2026-125253?
- Medium severity, with a CVSS score of 5.3, published 9 November 2026.
- Which products and versions are affected?
- Ffmpeg through 9.0.2.
- Is there a fix for CVE-2026-125253?
- Yes: fixed in FFmpeg 9.1 (merged in pull request #25232, merged 2026-10-25). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-125253 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-125253?
- Check whether you run Ffmpeg at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
How to fix
- Fixed in: FFmpeg 9.1 (merged in pull request #25232, merged 2026-10-25)
Technical details
The integer overflow occurs in cbs_vp9_split_fragment() when validating superframe index frame sizes on 32-bit builds. An attacker can supply a crafted VP9 packet with frame sizes close to 2^32, causing the size check to wrap and allowing out-of-bounds reads in the libavcodec buffer. The vulnerability requires no authentication or special privileges; the attacker only needs to deliver the malicious VP9 packet to a decoder.
Affected products
- FFmpeg FFmpeg through 9.0.2
Timeline
- 2026-11-09: disclosed
- 2026-10-25: patched: Fix merged in PR #25232