What is CVE-2026-1979?

CVE-2026-1979 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 2026-02-06.

How severe is CVE-2026-1979?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Buffer overflow in Mruby

CVE-2026-1979

A flaw has been found in mruby up to 3.4.0. This affects the function mrb_vm_exec of the file src/vm.c of the component JMPNOT-to-JMPIF Optimization. Executing a manipulation can lead to use after free. The attack needs to be launched locally. The exploit has been published and may be used. This patch is called e50f15c1c6e131fa7934355eb02b8173b13df415. It is advisable to implement a patch to correct this issue.

Vulnerability class: Buffer Overflow

EPSS: 0.002 (5.0th 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
N/a Mruby — versions 3.0, 3.1, 3.2

Weakness classification (CWE)

References

cna@vuldb.com (technical-description, VDB Entry, Third Party Advisory, vdb-entry)
cna@vuldb.com (signature, Permissions Required, permissions-required, VDB Entry)
cna@vuldb.com (VDB Entry, Third Party Advisory, third-party-advisory)
cna@vuldb.com (issue-tracking, Exploit, Issue Tracking)
cna@vuldb.com (issue-tracking, Exploit, exploit, Issue Tracking)
cna@vuldb.com (Patch, patch)
cna@vuldb.com (Product, product)

Frequently asked questions

What is CVE-2026-1979?: CVE-2026-1979 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 2026-02-06.
How severe is CVE-2026-1979?: Medium severity. CVSS v3 base score is 5.3 out of 10.