- 4.8MediumCVSS base score
- 0.18%Exploitation in 30 daysEPSS · top 92% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- YesPublic exploitsa reference or SSVC says so
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.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. A reference of the record is tagged as an exploit. CISA's SSVC rates its exploitation: a proof of concept is public.
Show the exploits1
References tagged exploit1 reference
- https://github.com/mruby/mruby/issues/6701#issue-3802609843 (opens in a new tab)exploitissue-tracking
Timeline
ID reserved
By VulDB
- 1 day later
· 1 day later
Published
- 17 days later
· 17 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| VulDBCNA (assigner) | 4.0 | Medium4.8 | 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 |
| VulDBCNA (assigner) | 3.1 | Medium5.3 | 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 |
| VulDBCNA (assigner) | 3.0 | Medium5.3 | 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 |
| VulDBCNA (assigner) | 2.0 | Medium4.3 | AV:L/AC:L/Au:S/C:P/I:P/A:P/E:POC/RL:OF/RC:C |
| NVDNVD · Analyzed | 4.0 | Low1.9 | 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 |
- EPSS (exploitation in 30 days)
- 0.18% · top 92% of all CVEs (12 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 4.8.
Affected products
mruby
- affected 3.0
- affected 3.1
- affected 3.2
- affected 3.3
- affected 3.4.0
References
References7
- VDB-344501 | mruby JMPNOT-to-JMPIF Optimization vm.c mrb_vm_exec use after free (opens in a new tab)vdb-entrytechnical-description
- VDB-344501 | CTI Indicators (IOB, IOC, IOA) (opens in a new tab)signaturepermissions-required
- Submit #743377 | mruby cda2567 Use After Free (opens in a new tab)third-party-advisory
- https://github.com/mruby/mruby/issues/6701 (opens in a new tab)issue-tracking
- https://github.com/mruby/mruby/issues/6701#issue-3802609843 (opens in a new tab)exploitissue-tracking
- https://github.com/sysfce2/mruby/commit/e50f15c1c6e131fa7934355eb02b8173b13df415 (opens in a new tab)patch
- https://github.com/mruby/mruby/ (opens in a new tab)product
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-5583 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-1979)Record last updated .