# OSV-2026-1294: UNKNOWN WRITE in av1_cdef_mse_calc_frame_mt

> A memory corruption vulnerability in the AV1 codec allows attackers to cause crashes or potentially execute code via crafted media files.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 17 Sep 2026

## What is OSV-2026-1294?

OSV-2026-1294 is a memory corruption vulnerability in libaom, published on 17 Sep 2026. 

### Official description

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=562150738

```
Crash type: UNKNOWN WRITE
Crash state:
av1_cdef_mse_calc_frame_mt
av1_cdef_search
encode_with_recode_loop_and_filter
```

## Which versions are affected by OSV-2026-1294?

1 open source package ship an affected version, including libaom.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libaom` | OSS-Fuzz | All versions | None |

## How do I fix OSV-2026-1294?

No fix has been published for OSV-2026-1294 yet. Limit exposure of the affected software until one is available.

## Is OSV-2026-1294 being exploited?

There is no known exploitation of OSV-2026-1294 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for OSV-2026-1294 and fix it if it is affected.

What it is: OSV-2026-1294 is a memory corruption vulnerability in libaom, published on 17 Sep 2026. 
Exploitation: There is no known exploitation of OSV-2026-1294 in the wild and no public exploit code.

Affected packages and fixed versions:
- libaom (OSS-Fuzz): affected all versions; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/OSV-2026-1294/ (Markdown: https://insights.sbomify.com/OSV-2026-1294/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/OSV-2026-1294

---
From sbomify Insights: https://insights.sbomify.com/OSV-2026-1294/
Summaries are generated and may contain mistakes; the official description above is the record.