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No exploitation reportedFix available

CVE-2020-15866

No exploitation reported by the sources we read.

  • Published2020-07-21
  • WeaknessCWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

mruby through 2.1.2-rc has a heap-based buffer overflow in the mrb_yield_with_class function in vm.c because of incorrect VM stack handling. It can be triggered via the stack_copy function.

Timeline

dates in UTC
  1. 2020-07-2115:15CVE publishedNVD

Versions per branch

NVD
Mruby
BranchAffectedFixed in
2.1≤ 2.1.1no fix published
2.1= 2.1.2no fix published
Debian debian linux
BranchAffectedFixed in
9.0= 9.0no fix published

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • mrubyUbuntu:26.10all versions · no fixed version listed
  • mrubyUbuntu:26.04:LTSall versions · no fixed version listed
  • mrubyUbuntu:25.10all versions · no fixed version listed
  • mrubyUbuntu:24.04:LTSall versions · no fixed version listed
  • mrubyUbuntu:22.04:LTSall versions · no fixed version listed
  • mrubyUbuntu:20.04:LTSall versions · no fixed version listed
  • mrubyUbuntu:18.04:LTSall versions · no fixed version listed
  • mrubyUbuntu:16.04:LTSall versions · no fixed version listed

17 more package ranges on OSV.dev

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2020-07-21
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-4f9x-p86g-x88m

Frequently asked questions

What is CVE-2020-15866?

mruby through 2.1.2-rc has a heap-based buffer overflow in the mrb_yield_with_class function in vm.c because of incorrect VM stack handling. It can be triggered via the stack_copy function.

Is CVE-2020-15866 actively exploited?

Active exploitation of CVE-2020-15866 has not been confirmed. Its EPSS score was 2.1% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-15866?

CVE-2020-15866 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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