How severe is CVE-2026-1979?

CVE-2026-1979 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-1979 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-1979?

CVE-2026-1979 affects Mruby. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-1979?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-1979 have an EU (EUVD) identifier?

Yes. CVE-2026-1979 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5583.

When was CVE-2026-1979 published?

CVE-2026-1979 was published on 2026-02-06 and last updated on 2026-06-17.

CVE-2026-1979

CVE-2026-1979 is a medium-severity vulnerability in Mruby with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-119.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 4.3
CVSS v4: 1.9
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-5583
Weakness: CWE-119
Affected product: Mruby
Published: 2026-02-06
Last modified: 2026-06-17

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-1979?: CVE-2026-1979 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-1979 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-1979?: CVE-2026-1979 affects Mruby. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-1979?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-1979 have an EU (EUVD) identifier?: Yes. CVE-2026-1979 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-5583.
When was CVE-2026-1979 published?: CVE-2026-1979 was published on 2026-02-06 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:mruby:mruby:*:*:*:*:*:ruby:*:*

More vulnerabilities in Mruby

CVE-2022-1286 — Critical (CVSS 9.8): heap-buffer-overflow in mrb_vm_exec in mruby/mruby in GitHub repository mruby/mruby prior to 3.2. Possible arbitrary…
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CVE-2022-1212 — Critical (CVSS 9.8): Use-After-Free in str_escape in mruby/mruby in GitHub repository mruby/mruby prior to 3.2. Possible arbitrary code…
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