# OSV-2021-562: Segv on unknown address in GC_generic_malloc_many

> A segmentation fault in the garbage collector's memory allocation routine can cause a denial of service in applications using the library.

- **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:** 26 Mar 2021

## What is OSV-2021-562?

OSV-2021-562 is a memory corruption vulnerability in w3m, published on 26 Mar 2021. 

### Official description

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=32453

```
Crash type: Segv on unknown address
Crash state:
GC_generic_malloc_many
GC_malloc_atomic
Strnew_size
```

## Which versions are affected by OSV-2021-562?

1 open source package ship an affected version, including w3m.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `w3m` | OSS-Fuzz | All versions | None |

## How do I fix OSV-2021-562?

No fix has been published for OSV-2021-562 yet. Limit exposure of the affected software until one is available.

## Is OSV-2021-562 being exploited?

There is no known exploitation of OSV-2021-562 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for OSV-2021-562 and fix it if it is affected.

What it is: OSV-2021-562 is a memory corruption vulnerability in w3m, published on 26 Mar 2021. 
Exploitation: There is no known exploitation of OSV-2021-562 in the wild and no public exploit code.

Affected packages and fixed versions:
- w3m (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-2021-562/ (Markdown: https://insights.sbomify.com/OSV-2021-562/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/OSV-2021-562

---
From sbomify Insights: https://insights.sbomify.com/OSV-2021-562/
Summaries are generated and may contain mistakes; the official description above is the record.