Buffer overflow in Mruby

CVE-2025-12875

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.

Vulnerability class: Buffer Overflow

EPSS: 0.002 (5.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L.

Affected products

  • Mruby — versions 3.4.0
  • N/a Mruby — versions 3.4.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-12875?
CVE-2025-12875 is a medium-severity vulnerability in Mruby, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 5.3/10. Published 2025-11-07.
How severe is CVE-2025-12875?
Medium severity. CVSS v3 base score is 5.3 out of 10.