GNU mtools: out-of-bounds write

GNU mtools

GNU mtools through 4.0.49 has an out-of-bounds write vulnerability, fixed in version 4.0.50

Do this now

No source names a fix yet: limit who can reach GNU mtools until one does.

Still cooking for GNU mtools.

First seen: 31 Oct 2026
Last update: 31 Oct 2026, 01:19 UTC
Identifiers: CVE-2026-118384
CVSS: 6.1
Source: news

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## GNU mtools: out-of-bounds write
Severity: medium. Patch status: fix status unknown.
Affected: GNU mtools
Ids: CVE-2026-118384

GNU mtools through 4.0.49 has an out-of-bounds write vulnerability, fixed in version 4.0.50

## Steps
1. Search the repo, its CI and infra config for GNU mtools. If present, report the version in use and whether it's affected.
2. GNU mtools <= 4.0.49: the CVE record names no fix; check the vendor advisory before assuming there is none. Until one ships: restrict network access to it.

## Fix by release line
| Line | State | Fix | Until then |
|---|---|---|---|
| GNU mtools <= 4.0.49 | not named in the CVE record | check the vendor advisory | restrict network access to it |

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-118384") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://seclists.org/oss-sec/2026/q4/455
https://pwned.coffee/i/gnu-mtools-out-of-bounds-write-cve-2026-118384

Timeline

31 Oct 2026, 01:19 UTC
Fix status: patched → unknown.
31 Oct 2026
First reported.

Receipt

Exploitation: No known exploitation
Fix by release line: Product Affected Fixed in Source
GNU mtools <= 4.0.49 fix not named in the CVE record: see vendor advisory CVE record (CNA) checked 31 Oct
Score: CVSS 6.1 (medium). CVSS 3.1 6.1 (CNA mitre) for CVE-2026-118384
Last checked: 31 Oct 2026, 01:19 UTC

Product	Affected	Fixed in	Source
GNU mtools	<= 4.0.49	fix not named in the CVE record: see vendor advisory	CVE record (CNA) checked 31 Oct

Sources: KEV – CVE record ✓ Vendor ✓

Sources

seclists.org: Fwd: GNU mtools 4.0.50 released, fixes CVE-2026-118384

Wrong fix version, or a source we missed? Send it back to chef@pwned.coffee with the source, and we'll correct it here.

Totalone coffee