OSV-2026-514 Heap-buffer-overflow in format_expand1
Not scored
Published
Check this codebase for OSV-2026-514 and fix it if it is affected.
What it is: OSV-2026-514 is a memory corruption vulnerability in tmux, published on 3 Apr 2026.
Exploitation: There is no known exploitation of OSV-2026-514 in the wild and no public exploit code.
Affected packages and fixed versions:
- tmux (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-2026-514/ (Markdown: https://insights.sbomify.com/OSV-2026-514/index.md)
A heap-buffer-overflow in format_expand1 can lead to crashes or potential code execution in the affected library.
- Exploited in the wild
- Not known
- Login needed
- Not stated
- Attackable
- Not stated
- Victim action needed
- Not stated
- Fix
- None listed
What is OSV-2026-514?
OSV-2026-514 is a memory corruption vulnerability in tmux, published on 3 Apr 2026.
Official description
OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=498472071
Crash type: Heap-buffer-overflow READ 1
Crash state:
format_expand1
format_expand
format-fuzzer.c
Which versions are affected by OSV-2026-514?
1 open source package ship an affected version, including tmux.
| Package | Affected | Fixed in |
|---|---|---|
tmux OSS-Fuzz | All versions | None |
How do I fix OSV-2026-514?
No fix has been published for OSV-2026-514 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is OSV-2026-514 being exploited?
There is no known exploitation of OSV-2026-514 in the wild and no public exploit code.