mruby up to 3.4.0 JMPNOT-to-JMPIF Optimization src/vm.c mrb_vm_exec use after free

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.2$0-$5k0.00

Summaryinfo

A vulnerability has been found in mruby up to 3.4.0 and classified as critical. This vulnerability affects the function mrb_vm_exec of the file src/vm.c of the component JMPNOT-to-JMPIF Optimization. The manipulation leads to use after free. This vulnerability is documented as CVE-2026-1979. The attack needs to be performed locally. Additionally, an exploit exists. Applying a patch is the recommended action to fix this issue.

Detailsinfo

A vulnerability was found in mruby up to 3.4.0. It has been rated as critical. This issue affects the function mrb_vm_exec of the file src/vm.c of the component JMPNOT-to-JMPIF Optimization. The manipulation with an unknown input leads to a use after free vulnerability. Using CWE to declare the problem leads to CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. Impacted is confidentiality, integrity, and availability.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-1979. The exploitation is known to be easy. An attack has to be approached locally. Technical details as well as a public exploit are known.

The exploit is available at github.com. It is declared as proof-of-concept. The vulnerability scanner Nessus provides a plugin with the ID 298288 (Linux Distros Unpatched Vulnerability : CVE-2026-1979), which helps to determine the existence of the flaw in a target environment.

Applying the patch e50f15c1c6e131fa7934355eb02b8173b13df415 is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the databases at Tenable (298288) and EUVD (EUVD-2026-5583). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.2

VulDB Base Score: 5.3
VulDB Temp Score: 4.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CNA Base Score: 5.3
CNA Vector: 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 298288
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-1979

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Patch: e50f15c1c6e131fa7934355eb02b8173b13df415

Timelineinfo

02/05/2026 Advisory disclosed
02/05/2026 +0 days VulDB entry created
02/28/2026 +23 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: 6701
Status: Confirmed

CVE: CVE-2026-1979 (🔒)
GCVE (CVE): GCVE-0-2026-1979
GCVE (VulDB): GCVE-100-344501
EUVD: 🔒
scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 02/05/2026 14:49
Updated: 02/28/2026 01:57
Changes: 02/05/2026 14:49 (60), 02/06/2026 07:24 (30), 02/07/2026 11:50 (2), 02/07/2026 13:18 (1), 02/28/2026 01:57 (12)
Complete: 🔍
Submitter: Oneafter
Cache ID: 216::103

Submitinfo

Accepted

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Want to stay up to date on a daily basis?

Enable the mail alert feature now!