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🛡️ CVE-2026-1979 — mruby

🟡 CVSS 5.3 — Medium ⚠️ Exploit Public CWE-119 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

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.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality low, integrity low, availability low.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

  • Attack vector: Local — a local account, shell or session on the host is needed.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: Low — limited, and the attacker does not choose what is affected.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: Low — limited, and the attacker does not choose what is affected.

Weakness class

CVE-2026-1979 is classified as CWE-119: Improper Restriction of Operations within Memory Buffer Bounds. A read or write is performed without confirming it stays inside the allocated buffer, corrupting adjacent memory.

Affected software

CVE-2026-1979 is recorded against 1 package.

  • mruby (fixed in 3.4.0)

Timeline and source

Published on 6 February 2026 and last revised on 17 June 2026. A public exploit is known to exist, which raises the urgency of patching considerably. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com
github.com
github.com
vuldb.com
vuldb.com
vuldb.com

Other advisories for this package

mruby has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-119: Improper Restriction of Operations within Memory Buffer Bounds) in other software:

CVE-2026-1979 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity MEDIUM
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CWE CWE-119
Public Exploit ⚠️ Yes
Source NVD
Published 2026-02-06
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
mruby — 3.4.0

Similar Threats

Exploit Protection

Are you running mruby?

CVE-2026-1979 carries CVSS 5.3 Medium rating and a public exploit already exists. BotEraser checks your installation against this and other known CVE records, and blocks IPs associated with exploit activity.

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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