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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.

PUBLISHED Reserved 2026-02-05 | Published 2026-02-06 | Updated 2026-02-23 | Assigner VulDB




MEDIUM: 4.8CVSS: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
MEDIUM: 5.3CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C
MEDIUM: 5.3CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L/E:P/RL:O/RC:C
4.3AV:L/AC:L/Au:S/C:P/I:P/A:P/E:POC/RL:OF/RC:C

Problem types

Use After Free

Memory Corruption

Timeline

2026-02-05:Advisory disclosed
2026-02-05:VulDB entry created
2026-02-07:VulDB entry last update

Credits

Oneafter (VulDB User) reporter

References

vuldb.com/?id.344501 (VDB-344501 | mruby JMPNOT-to-JMPIF Optimization vm.c mrb_vm_exec use after free) vdb-entry technical-description

vuldb.com/?ctiid.344501 (VDB-344501 | CTI Indicators (IOB, IOC, IOA)) signature permissions-required

vuldb.com/?submit.743377 (Submit #743377 | mruby cda2567 Use After Free) third-party-advisory

github.com/mruby/mruby/issues/6701 issue-tracking

github.com/mruby/mruby/issues/6701 exploit issue-tracking

github.com/...ommit/e50f15c1c6e131fa7934355eb02b8173b13df415 patch

github.com/mruby/mruby/ product

cve.org (CVE-2026-1979)

nvd.nist.gov (CVE-2026-1979)

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