Use After Free Flaw in mruby by mruby
CVE-2026-1979

4.8MEDIUM

Key Information:

Vendor

mruby

Status
Mruby
Vendor
CVE Published:
6 February 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-1979?

A vulnerability exists in mruby versions up to 3.4.0, specifically in the mrb_vm_exec function within the JMPNOT-to-JMPIF Optimization component. This weakness allows an attacker to execute a manipulation that can result in a use after free condition. The attack needs to be launched locally, and an exploit has been published, suggesting an immediate need for remediation. A patch is available as e50f15c1c6e131fa7934355eb02b8173b13df415 to address this issue effectively.

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Affected Version(s)

mruby 3.0

mruby 3.1

mruby 3.2

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-1979 - Proof of Concept

References

https://vuldb.com/?id.344501
vdb-entrytechnical-description
https://vuldb.com/?ctiid.344501
signaturepermissions-required
https://vuldb.com/?submit.743377
third-party-advisory

CVSS V4

Score:
4.8
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
Low
Availability:
Low
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

Oneafter (VulDB User)
JSON
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