# OSV-2021-725: UNKNOWN READ in libfsext_directory_entry_read_data

> A memory corruption vulnerability in libfsext allows attackers to cause a denial of service via crafted directory entries.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 5 May 2021

## What is OSV-2021-725?

OSV-2021-725 is a memory corruption vulnerability in libyal, published on 5 May 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=33935

```
Crash type: UNKNOWN READ
Crash state:
libfsext_directory_entry_read_data
libfsext_directory_read_inline_data
libfsext_directory_read_file_io_handle
```

## Which versions are affected by OSV-2021-725?

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


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

## How do I fix OSV-2021-725?

No fix has been published for OSV-2021-725 yet. Limit exposure of the affected software until one is available.

## Is OSV-2021-725 being exploited?

There is no known exploitation of OSV-2021-725 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for OSV-2021-725 and fix it if it is affected.

What it is: OSV-2021-725 is a memory corruption vulnerability in libyal, published on 5 May 2021. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of OSV-2021-725 in the wild and no public exploit code.

Affected packages and fixed versions:
- libyal (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-2021-725/ (Markdown: https://insights.sbomify.com/OSV-2021-725/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/OSV-2021-725

---
From sbomify Insights: https://insights.sbomify.com/OSV-2021-725/
Summaries are generated and may contain mistakes; the official description above is the record.