# CVE-2026-125253: FFmpeg integer overflow in VP9 superframe parsing

Source: https://junglewise.ai/threats/cve-2026-125253-ffmpeg-through-9-0-2-contains-an-integer-overflow-in-cbs-vp9  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-09. Updated: 2026-11-09  
License: CC BY 4.0 with a link back

CVE-2026-125253 · Severity: medium · CVSS 5.3 · Published 2026-11-09

FFmpeg is a widely-used multimedia library that decodes video formats including VP9. A flaw in parsing VP9 video packets can cause integer overflow on 32-bit systems, allowing an attacker to craft a malicious video file that crashes applications using FFmpeg to play it. This could be exploited to deny service to media playback or streaming applications.

Technologies: [Ffmpeg](https://junglewise.ai/threats/technologies/ffmpeg). Vendors: [Ffmpeg](https://junglewise.ai/threats/vendors/ffmpeg).

## 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

## References

- [https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25232](https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25232)
- [https://github.com/FFmpeg/FFmpeg](https://github.com/FFmpeg/FFmpeg)

## Related threats

- [FFmpeg heap out-of-bounds read in v4l2_buffers](https://junglewise.ai/threats/cve-2026-125270-ffmpeg-through-9-0-2-contains-a-heap-out-of-bounds-read)
- [FFmpeg double free in H.264 SEI message handling](https://junglewise.ai/threats/cve-2026-125269-ffmpeg-through-9-0-2-contains-a-double-free-vulnerability-in)
- [FFmpeg heap out-of-bounds write in APAC decoder](https://junglewise.ai/threats/cve-2026-125267-ffmpeg-before-8-1-3-and-9-x-before-9-0-2-contains-a-heap-out-of)
- [FFmpeg use-after-free in NVIDIA codec decoding](https://junglewise.ai/threats/cve-2026-125265-ffmpeg-through-9-0-2-contains-a-use-after-free-vulnerability-in)
- [FFmpeg JPEG XL parser uncontrolled resource consumption](https://junglewise.ai/threats/cve-2026-125264-ffmpeg-through-9-0-2-contains-an-uncontrolled-resource)