mruby JMPNOT-to-JMPIF Optimization vm.c mrb_vm_exec use after free
Summary
| CVE | CVE-2026-1979 |
|---|---|
| State | PUBLISHED |
| Assigner | VulDB |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-02-06 05:16:12 UTC |
| Updated | 2026-04-29 01:00:01 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 1.9 LOW from [email protected]
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Problem Types: CWE-119 | CWE-416 | CWE-416 Use After Free | CWE-119 Memory Corruption
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 1.9 | LOW | CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/C... |
| 4.0 | CNA | DECLARED | 4.8 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P |
| 3.1 | [email protected] | Primary | 5.5 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | [email protected] | Secondary | 5.3 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L |
| 3.1 | CNA | DECLARED | 5.3 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C |
| 3.0 | CNA | DECLARED | 5.3 | MEDIUM | CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C |
| 2.0 | [email protected] | Secondary | 4.3 | AV:L/AC:L/Au:S/C:P/I:P/A:P | |
| 2.0 | CNA | DECLARED | 4.3 | AV:L/AC:L/Au:S/C:P/I:P/A:P/E:POC/RL:OF/RC:C |
CVSS v4.0 Breakdown
Attack Vector
LocalAttack Complexity
LowAttack Requirements
NonePrivileges Required
LowUser Interaction
NoneConfidentiality
LowIntegrity
LowAvailability
LowSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
NoneAvailability
HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS v3.0 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
LowIntegrity
LowAvailability
LowCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/mruby/mruby/issues/6701 | [email protected] | github.com | Exploit, Issue Tracking |
| github.com/mruby/mruby | [email protected] | github.com | Product |
| github.com/mruby/mruby/issues/6701 | [email protected] | github.com | Exploit, Issue Tracking |
| github.com/sysfce2/mruby/commit/e50f15c1c6e131fa7934355eb02b8173b13df415 | [email protected] | github.com | Patch |
| vuldb.com | [email protected] | vuldb.com | Third Party Advisory, VDB Entry |
| vuldb.com | [email protected] | vuldb.com | Third Party Advisory, VDB Entry |
| vuldb.com | [email protected] | vuldb.com | Permissions Required, VDB Entry |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Oneafter (VulDB User) (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-02-05T00:00:00.000Z | Advisory disclosed |
| CNA | 2026-02-05T01:00:00.000Z | VulDB entry created |
| CNA | 2026-02-07T13:18:56.000Z | VulDB entry last update |
There are currently no legacy QID mappings associated with this CVE.