# CVE-2025-13120: mruby array.c sort_cmp use after free

> A use-after-free vulnerability in mruby's sort_cmp function allows local attackers to potentially execute code or cause denial of service.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P`)
- **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:** 13 Nov 2025
- **Updated:** 4 Mar 2026
- **Also known as:** DEBIAN-CVE-2025-13120, GHSA-j383-q79v-268x, UBUNTU-CVE-2025-13120

## What is CVE-2025-13120?

CVE-2025-13120 is a medium-severity use after free vulnerability in mruby, published on 13 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability has been found in mruby up to 3.4.0. This vulnerability affects the function sort_cmp of the file src/array.c. Such manipulation leads to use after free. An attack has to be approached locally. The exploit has been disclosed to the public and may be used. The name of the patch is eb398971bfb43c38db3e04528b68ac9a7ce509bc. It is advisable to implement a patch to correct this issue.

Weakness: CWE-416 (Use After Free), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2025-13120?

It affects 1 product.


Products: Mruby Mruby.

## How do I fix CVE-2025-13120?

Apply the vendor's patch.

## Is CVE-2025-13120 being exploited?

There is no known exploitation of CVE-2025-13120 in the wild and no public exploit code.

## Other vulnerabilities in mruby

- [CVE-2020-6838](https://insights.sbomify.com/CVE-2020-6838/): Use after free in n/a (critical 9.8)
- [CVE-2020-6839](https://insights.sbomify.com/CVE-2020-6839/): Memory corruption in n/a (critical 9.8)
- [CVE-2020-6840](https://insights.sbomify.com/CVE-2020-6840/): Use after free in n/a (critical 9.8)
- [CVE-2018-10199](https://insights.sbomify.com/CVE-2018-10199/): Use after free in n/a (critical 9.8)
- [CVE-2022-1212](https://insights.sbomify.com/CVE-2022-1212/): Use-After-Free in str_escape in mruby/mruby in mruby/mruby (critical 9.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-13120 and fix it if it is affected.

What it is: CVE-2025-13120 is a medium-severity use after free vulnerability in mruby, published on 13 Nov 2025. 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-2025-13120 in the wild and no public exploit code.

Affected product: mruby. 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-2025-13120/ (Markdown: https://insights.sbomify.com/CVE-2025-13120/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-13120
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-13120
- OSV: https://osv.dev/vulnerability/CVE-2025-13120

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-13120/
Summaries are generated and may contain mistakes; the official description above is the record.