# CVE-2026-4012: rxi fe fe.c read_ out-of-bounds

> A local attacker can trigger an out-of-bounds read in the fe language interpreter, potentially causing crashes or leaking memory.

- **Severity:** Medium 4.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/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:** No
- **Published:** 12 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-jw4f-7h4g-j7fj

## What is CVE-2026-4012?

CVE-2026-4012 is a medium-severity memory corruption vulnerability in rxi fe, published on 12 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability was determined in rxi fe up to ed4cda96bd582cbb08520964ba627efb40f3dd91. The impacted element is the function read_ of the file src/fe.c. This manipulation with the input 1 causes out-of-bounds read. The attack requires local access. The exploit has been publicly disclosed and may be utilized. This product uses a rolling release model to deliver continuous updates. As a result, specific version information for affected or updated releases is not available. The project was informed of the problem early through an issue report but has not responded yet.

Weakness: CWE-125 (Out-of-bounds Read), CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer)

## Which versions are affected by CVE-2026-4012?


## How do I fix CVE-2026-4012?

No fix has been published for CVE-2026-4012 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-4012 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4012 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-4012 and fix it if it is affected.

What it is: CVE-2026-4012 is a medium-severity memory corruption vulnerability in rxi fe, published on 12 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-4012 exists.

Affected product: rxi fe. 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-2026-4012/ (Markdown: https://insights.sbomify.com/CVE-2026-4012/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-4012
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-4012
- OSV: https://osv.dev/vulnerability/CVE-2026-4012

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-4012/
Summaries are generated and may contain mistakes; the official description above is the record.