OSV-2026-726 Use-after-poison in md_build_attribute
Not scored
Published
Check this codebase for OSV-2026-726 and fix it if it is affected.
What it is: OSV-2026-726 is an use after free vulnerability in md4c, published on 14 May 2026.
Exploitation: There is no known exploitation of OSV-2026-726 in the wild and no public exploit code.
Affected packages and fixed versions:
- md4c (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-2026-726/ (Markdown: https://insights.sbomify.com/OSV-2026-726/index.md)
A use-after-poison vulnerability in the markdown parser allows attackers to cause a denial of service via crafted input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Not stated
- Victim action needed
- Not needed
- Fix
- None listed
What is OSV-2026-726?
OSV-2026-726 is an use after free vulnerability in md4c, published on 14 May 2026.
Official description
OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=512429151
Crash type: Use-after-poison READ 1
Crash state:
md_build_attribute
md_process_all_blocks
md_parse
Which versions are affected by OSV-2026-726?
1 open source package ship an affected version, including md4c.
| Package | Affected | Fixed in |
|---|---|---|
md4c OSS-Fuzz | All versions | None |
How do I fix OSV-2026-726?
No fix has been published for OSV-2026-726 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is OSV-2026-726 being exploited?
There is no known exploitation of OSV-2026-726 in the wild and no public exploit code.