# CVE-2025-13397: mrubyc alloc.c mrbc_raw_realloc null pointer dereference

> A local attacker can cause a denial of service in mrubyc via a null pointer dereference in the memory reallocation function.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X`)
- **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:** No
- **Published:** 19 Nov 2025
- **Updated:** 19 Nov 2025
- **Also known as:** GHSA-99jr-qh2r-jwfm

## What is CVE-2025-13397?

CVE-2025-13397 is a medium-severity vulnerability in mrubyc, published on 19 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A security vulnerability has been detected in mrubyc up to 3.4. This impacts the function mrbc_raw_realloc of the file src/alloc.c. Such manipulation of the argument ptr leads to null pointer dereference. An attack has to be approached locally. The name of the patch is 009111904807b8567262036bf45297c3da8f1c87. It is advisable to implement a patch to correct this issue.

Weakness: CWE-476 (NULL Pointer Dereference), CWE-404 (Improper Resource Shutdown or Release)

## Which versions are affected by CVE-2025-13397?

It affects 1 product.


Products: S-Itoc Mruby\/C.

## How do I fix CVE-2025-13397?

No fix has been published for CVE-2025-13397 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-13397 being exploited?

There is no known exploitation of CVE-2025-13397 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-13397 and fix it if it is affected.

What it is: CVE-2025-13397 is a medium-severity vulnerability in mrubyc, published on 19 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-2025-13397 in the wild and no public exploit code.

Affected product: mrubyc. 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-2025-13397/ (Markdown: https://insights.sbomify.com/CVE-2025-13397/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-13397
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-13397
- OSV: https://osv.dev/vulnerability/CVE-2025-13397

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-13397/
Summaries are generated and may contain mistakes; the official description above is the record.