# CVE-2023-29421: Memory corruption in n/a

> An out-of-bounds write in the bzip3 library allows attackers to execute arbitrary code or cause denial of service via crafted compressed data.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 6 Apr 2023
- **Updated:** 12 Feb 2025
- **Also known as:** DEBIAN-CVE-2023-29421, GHSA-jxf3-h258-gvf9, UBUNTU-CVE-2023-29421

## What is CVE-2023-29421?

CVE-2023-29421 is a high-severity memory corruption vulnerability in n/a, published on 6 Apr 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

An issue was discovered in libbzip3.a in bzip3 before 1.2.3. There is an out-of-bounds write in bz3_decode_block.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2023-29421?

It affects 1 product.


Products: Bzip3 Project Bzip3.

## How do I fix CVE-2023-29421?

Upgrade to a fixed version.

## Is CVE-2023-29421 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-29421 exists.

## Other vulnerabilities in n/a

- [CVE-2023-29415](https://insights.sbomify.com/CVE-2023-29415/): Denial of service in n/a (medium 6.5)
- [CVE-2023-29416](https://insights.sbomify.com/CVE-2023-29416/): Memory corruption in n/a (medium 6.5)
- [CVE-2023-29417](https://insights.sbomify.com/CVE-2023-29417/): Memory corruption in n/a (medium 6.5)
- [CVE-2023-29418](https://insights.sbomify.com/CVE-2023-29418/): Memory corruption in n/a (medium 6.5)
- [CVE-2023-29419](https://insights.sbomify.com/CVE-2023-29419/): Memory corruption in n/a (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-29421 and fix it if it is affected.

What it is: CVE-2023-29421 is a high-severity memory corruption vulnerability in n/a, published on 6 Apr 2023. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2023-29421 exists.

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-2023-29421/ (Markdown: https://insights.sbomify.com/CVE-2023-29421/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-29421
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-29421
- OSV: https://osv.dev/vulnerability/CVE-2023-29421

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-29421/
Summaries are generated and may contain mistakes; the official description above is the record.