CVE-2026-1979

mruby JMPNOT-to-JMPIF Optimization vm.c mrb_vm_exec use after free

Assigner: VulDB
Reserved: 05.02.2026 Published: 06.02.2026 Updated: 06.02.2026

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.

Metrics

CVSS Vector: 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
CVSS Score: 4.8

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Local	Confidentiality	Low	Confidentiality	None
Attack Complexity	Low	Integrity	Low	Integrity	None
Attack Requirements	None	Availability	Low	Availability	None
Privileges Required	Low
User Interaction	None

CVSS 4.0

CVSS Vector: 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
CVSS Score: 5.3

Attack Vector	Local	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	Low
Privileges Required	Low	Integrity Impact	Low
User Interaction	None	Availability Impact	Low

CVSS 3.1

CVSS Vector: 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
CVSS Score: 5.3

Attack Vector	Local	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	Low
Privileges Required	Low	Integrity Impact	Low
User Interaction	None	Availability Impact	Low

CVSS 3.0

CVSS Vector: AV:L/AC:L/Au:S/C:P/I:P/A:P/E:POC/RL:OF/RC:C
CVSS Score: 4.3

Access Vector	Local	Confidentiality Impact	Partial
Access Complexity	Low	Integrity Impact	Partial
Authentication	Single	Availability Impact	Partial

CVSS 2.0

Product Status

Vendor	n/a
Product	mruby
Versions	Version 3.0 is affected Version 3.1 is affected Version 3.2 is affected Version 3.3 is affected Version 3.4.0 is affected

Vendor

n/a

Product

mruby

Versions

Version 3.0 is affected
Version 3.1 is affected
Version 3.2 is affected
Version 3.3 is affected
Version 3.4.0 is affected

Credits

Oneafter (VulDB User) reporter

References

Problem Types