# CVE-2021-43413: Privilege escalation in n/a

> A shared pager port in GNU Hurd allows local attackers to modify readable files, leading to trivial full root access.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 7 Nov 2021
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-4gqc-53g7-25x6

## What is CVE-2021-43413?

CVE-2021-43413 is a high-severity vulnerability in n/a, published on 7 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

An issue was discovered in GNU Hurd before 0.9 20210404-9. A single pager port is shared among everyone who mmaps a file, allowing anyone to modify any files that they can read. This can be trivially exploited to get full root access.

## Which versions are affected by CVE-2021-43413?

It affects 1 product.


Products: Gnu Hurd.

## How do I fix CVE-2021-43413?

No fix has been published for CVE-2021-43413 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-43413 being exploited?

There is no known exploitation of CVE-2021-43413 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2021-43412](https://insights.sbomify.com/CVE-2021-43412/): Use after free in n/a (high 7.8)
- [CVE-2021-43411](https://insights.sbomify.com/CVE-2021-43411/): Race condition in n/a (high 7.5)
- [CVE-2021-43414](https://insights.sbomify.com/CVE-2021-43414/): Auth bypass in n/a (high 7.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-43413 and fix it if it is affected.

What it is: CVE-2021-43413 is a high-severity vulnerability in n/a, published on 7 Nov 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-43413 in the wild and no public exploit code.

Affected product: n/a. No package-level version data is available, so check the vendor advisory linked from the reference page.

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/CVE-2021-43413/ (Markdown: https://insights.sbomify.com/CVE-2021-43413/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-43413
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-43413
- OSV: https://osv.dev/vulnerability/CVE-2021-43413

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-43413/
Summaries are generated and may contain mistakes; the official description above is the record.