CVE-2025-12875 mruby array.c ary_fill_exec out-of-bounds write

Medium 4.8 Published 7 Nov 2025 Updated 24 Feb 2026

Local attackers can exploit an out-of-bounds write in mruby's array fill function to potentially execute arbitrary code or escalate privileges.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-12875?

CVE-2025-12875 is a medium-severity memory corruption vulnerability in mruby, published on 7 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

A weakness has been identified in mruby 3.4.0. This vulnerability affects the function ary_fill_exec of the file mrbgems/mruby-array-ext/src/array.c. Executing a manipulation of the argument start/length can lead to out-of-bounds write. The attack needs to be launched locally. The exploit has been made available to the public and could be used for attacks. This patch is called 93619f06dd378db6766666b30c08978311c7ec94. It is best practice to apply a patch to resolve this issue.

Weakness: CWE-787, CWE-119

Which versions are affected by CVE-2025-12875?

It affects 1 product.

Products include Mruby Mruby.

How do I fix CVE-2025-12875?

No fix has been published for CVE-2025-12875 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2025-12875 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-12875 exists.

Sources

Also known as GHSA-q269-xqww-45mm, UBUNTU-CVE-2025-12875.