CVE-2026-86547 mrubyc through 4.0.0 NULL Pointer Dereference via OP_ENTER
Attackers can crash applications embedding mrubyc by providing malicious bytecode, causing a denial of service via null pointer dereference.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-86547?
CVE-2026-86547 is a medium-severity vulnerability in mrubyc, published on 9 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
mrubyc through 4.0.0 contains a null pointer dereference vulnerability in the op_enter() handler in src/vm.c when processing untrusted bytecode. Attackers can craft malicious .mrb bytecode files with OP_ENTER instructions at the top level to crash the embedding application and cause denial of service.
Weakness: CWE-476
Which versions are affected by CVE-2026-86547?
How do I fix CVE-2026-86547?
No fix has been published for CVE-2026-86547 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-86547 being exploited?
There is no known exploitation of CVE-2026-86547 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Sources
Also known as GHSA-42q4-rvcw-q7wc.