# CVE-2021-25684: apport can be stalled by reading a FIFO

> An attacker can cause the apport crash reporting tool to hang by directing it to read from a FIFO, leading to a denial of service.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 11 Jun 2021
- **Updated:** 3 Nov 2025
- **Also known as:** GHSA-5wpx-42qp-2c7p, UBUNTU-CVE-2021-25684

## What is CVE-2021-25684?

CVE-2021-25684 is a high-severity denial of service vulnerability in Canonical apport, published on 11 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

It was discovered that apport in data/apport did not properly open a report file to prevent hanging reads on a FIFO.

Weakness: CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2021-25684?

It affects 1 product.


Products: Canonical Apport.

## How do I fix CVE-2021-25684?

Apply the vendor's patch.

## Is CVE-2021-25684 being exploited?

There is no known exploitation of CVE-2021-25684 in the wild and no public exploit code.

## Other vulnerabilities in Canonical apport

- [CVE-2021-25682](https://insights.sbomify.com/CVE-2021-25682/): apport improperly parses /proc/pid/status (high 8.8)
- [CVE-2021-25683](https://insights.sbomify.com/CVE-2021-25683/): apport improperly parses /proc/pid/stat (high 8.8)
- [CVE-2021-3899](https://insights.sbomify.com/CVE-2021-3899/): Race condition in Apport (high 7.8)
- [CVE-2022-1242](https://insights.sbomify.com/CVE-2022-1242/): Other in Apport (high 7.8)
- [CVE-2023-1326](https://insights.sbomify.com/CVE-2023-1326/): local privilege escalation in apport-cli (high 7.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-25684 and fix it if it is affected.

What it is: CVE-2021-25684 is a high-severity denial of service vulnerability in Canonical apport, published on 11 Jun 2021. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-25684 in the wild and no public exploit code.

Affected product: Canonical apport. 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-2021-25684/ (Markdown: https://insights.sbomify.com/CVE-2021-25684/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25684
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25684
- OSV: https://osv.dev/vulnerability/CVE-2021-25684

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-25684/
Summaries are generated and may contain mistakes; the official description above is the record.