CVE-2026-79590

A NULL pointer dereference vulnerability exists in the Prism parser component of mruby 4.0.0. An...

6.5 Medium

A NULL pointer dereference vulnerability exists in the Prism parser component of mruby 4.0.0. An attacker can provide a specially crafted Ruby source file that triggers the parser to pass a NULL pointer to nonnull string handling functions, resulting in undefined behavior and application crash.

Attack profile

How easy it is to exploit

Attack vector: Network
Complexity: Low
Privileges needed: None
User interaction: Required

What an attacker can affect

Confidentiality: None
Integrity: None
Availability: High

Exploit likelihood

0.37%Up 0.2 points since Sep 11, 2026

What each source reports

CVE List Score used 6.5

Record: CVE-2026-79590
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness: CWE-476
Updated: 2026-11-02

EUVDEUVD-2026-75871 6.5

Record: EUVD-2026-75871
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-02

GitHub AdvisoriesGHSA-q9f2-rhj2-x3xg 6.5

A NULL pointer dereference vulnerability exists in the Prism parser component of mruby 4.0.0. An...

Record: GHSA-q9f2-rhj2-x3xg
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness: CWE-476
Updated: 2026-11-02

NVD 6.5

Record: CVE-2026-79590
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Weakness: CWE-476
Updated: 2026-11-02

OSV 6.5

Record: CVE-2026-79590
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVDEBIAN-CVE-2026-79590 6.5

Record: DEBIAN-CVE-2026-79590
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-02

OSVUBUNTU-CVE-2026-79590 6.5

Record: UBUNTU-CVE-2026-79590
CVSS 3.1: 6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Updated: 2026-11-02

Affected packages

Affected packages
Package	Affected	Fixed
`mruby` Debian:12	All versions, plus listed versions 3.1.0-33.2.0-13.2.0-23.3.0-13.3.0~rc2-1 Show 6 moreShow less 3.4.0-13.4.0-1~exp13.4.0-1~exp23.4.0-23.4.0-34.0.0-1	None known
`mruby` Debian:13	All versions, plus listed versions 3.3.0-13.4.0-13.4.0-1~exp13.4.0-1~exp23.4.0-23.4.0-34.0.0-1	None known
`mruby` Debian:14	All versions, plus listed versions 3.3.0-13.4.0-13.4.0-1~exp13.4.0-1~exp23.4.0-23.4.0-34.0.0-1	None known
`mruby` Ubuntu:16.04:LTS	All versions, plus listed versions 1.1.0+20150817+gita1731254-11.1.0+20150906+git1cbbb7e1-11.2.0+20160315+git4f20d58a-1	None known
`mruby` Ubuntu:18.04:LTS	All versions, plus listed versions 1.3.0-11.3.0+20170925+git38185028-11.3.0+20171029+git77edafb0-11.4.0-1	None known
`mruby` Ubuntu:20.04:LTS	All versions, plus listed versions 2.0.0-1	None known
`mruby` Ubuntu:22.04:LTS	All versions, plus listed versions 2.1.2-33.0.0-13.0.0-3	None known
`mruby` Ubuntu:24.04:LTS	All versions, plus listed versions 3.2.0-13.2.0-2	None known
`mruby` Ubuntu:26.10	All versions, plus listed versions 3.4.0-23.4.0-34.0.0-1	None known
`mruby` Ubuntu:26.04:LTS	All versions, plus listed versions 3.3.0-13.4.0-2	None known

History

History
Recorded	Changed	Sources
Nov 2, 2026	first indexed	CVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-79590 is a medium vulnerability (CVSS 6.5) in mruby, published September 10, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.37%, the 30th percentile. No source names a fixed version.