CVE-2026-6042 musl libc GB18030 4-byte Decoder iconv.c iconv algorithmic complexity
A local attacker can cause denial of service in musl libc via inefficient algorithmic complexity in the GB18030 iconv decoder.
- 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
What is CVE-2026-6042?
CVE-2026-6042 is a medium-severity denial of service vulnerability in musl libc, published on 10 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A security flaw has been discovered in musl libc up to 1.2.6. Affected is the function iconv of the file src/locale/iconv.c of the component GB18030 4-byte Decoder. Performing a manipulation results in inefficient algorithmic complexity. The attack must be initiated from a local position. To fix this issue, it is recommended to deploy a patch.
Which versions are affected by CVE-2026-6042?
How do I fix CVE-2026-6042?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-6042 being exploited?
There is no known exploitation of CVE-2026-6042 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as ALPINE-CVE-2026-6042, BELL-CVE-2026-6042, DEBIAN-CVE-2026-6042, ECHO-7274-4b19-c757, GHSA-2qh3-3rmv-x43w, ROOT-OS-ALPINE-317-CVE-2026-6042 and 1 more.