CVE-2026-1979
mruby JMPNOT-to-JMPIF Optimization vm.c mrb_vm_exec use after free
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
mruby JMPNOT-to-JMPIF Optimization vm.c mrb_vm_exec use after free
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.
- Record
CVE-2026-1979- CVSS 4.0
- 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 - CVSS 3.1
- 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 - CVSS 3.0
- 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 - CVSS 2.0
- 4.3
AV:L/AC:L/Au:S/C:P/I:P/A:P/E:POC/RL:OF/RC:C - Weakness
- CWE-416, CWE-119
- Updated
- 2026-11-02
EUVDEUVD-2026-5583
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.
- Record
EUVD-2026-5583- CVSS 4.0
- 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 - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-gxgq-rpmr-r8xr
A flaw has been found in mruby up to 3.4.0. This affects the function mrb_vm_exec of the file src...
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.
- Record
GHSA-gxgq-rpmr-r8xr- CVSS 4.0
- 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/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 3.1
- 5.3 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-119
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2026-1979- CVSS 4.0
- 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/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 3.1
- 5.3 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L - CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - CVSS 2.0
- 4.3 Medium
AV:L/AC:L/Au:S/C:P/I:P/A:P - Weakness
- CWE-119, CWE-416
- Updated
- 2026-11-02
OSV
mruby JMPNOT-to-JMPIF Optimization vm.c mrb_vm_exec use after free
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.
- Record
CVE-2026-1979- CVSS 4.0
- 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 - Weakness
- CWE-119, CWE-416
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-1979
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.
- Record
DEBIAN-CVE-2026-1979- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-1979
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.
- Record
UBUNTU-CVE-2026-1979- CVSS 4.0
- 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 - CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
mrubyDebian:12 |
All versions, plus listed versions 3.1.0-33.2.0-13.2.0-23.3.0-13.3.0~rc2-1 Show 6 moreShow less3.4.0-13.4.0-1~exp13.4.0-1~exp23.4.0-23.4.0-34.0.0-1 |
None known |
mrubyDebian:13 |
All versions, plus listed versions 3.3.0-13.4.0-13.4.0-1~exp13.4.0-1~exp23.4.0-23.4.0-34.0.0-1 |
None known |
mrubyDebian:14 |
before 4.0.0-1, plus listed versions 3.3.0-13.4.0-13.4.0-1~exp13.4.0-1~exp23.4.0-23.4.0-3 |
4.0.0-1 |
mrubyUbuntu:16.04:LTS |
All versions, plus listed versions 1.1.0+20150817+gita1731254-11.1.0+20150906+git1cbbb7e1-11.2.0+20160315+git4f20d58a-1 |
None known |
mrubyUbuntu:18.04:LTS |
All versions, plus listed versions 1.3.0-11.3.0+20170925+git38185028-11.3.0+20171029+git77edafb0-11.4.0-1 |
None known |
mrubyUbuntu:20.04:LTS |
All versions, plus listed versions 2.0.0-1 |
None known |
mrubyUbuntu:22.04:LTS |
All versions, plus listed versions 2.1.2-33.0.0-13.0.0-3 |
None known |
mrubyUbuntu:24.04:LTS |
All versions, plus listed versions 3.2.0-13.2.0-2 |
None known |
mrubyUbuntu:25.10 |
All versions, plus listed versions 3.3.0-1 |
None known |
mrubyUbuntu:26.10 |
All versions, plus listed versions 3.4.0-23.4.0-34.0.0-1 |
None known |
mrubyUbuntu:26.04:LTS |
All versions, plus listed versions 3.3.0-13.4.0-2 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-1979 is a medium vulnerability (CVSS 4.8) in Mruby, published February 6, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.18%, the 7th percentile. Fixed in mruby 4.0.0-1.