Public vulnerability disclosure

CVE-2026-118762

Monkeytype: fork PR can execute code with elevated GITHUB_TOKEN

publishedCWE-829

Monkeytype is a minimalistic and customizable typing test. Prior to 26.43.0, the .github/workflows/fix-formatting.yml workflow runs on pull_request_target with repository write permissions, checks out a fork pull request, installs dependencies from the fork's package.json, and invokes the fork-controlled oxfmt binary. Because actions/checkout persists the elevated GITHUB_TOKEN in Git configuration until after untrusted code executes, an external contributor whose pull request receives the format label can run arbitrary code, read or exfiltrate the token, and push repository content or modify pull requests and issues. The issue affects the repository CI workflow, not the Monkeytype application or user data. This issue is fixed in version 26.43.0.

Technical severity9.3 criticalCVSS 3.1 · CNA: GitHub_M
Published2026-10-29Source updated 2026-11-04
Collected2026-11-042 attributed sources

Fixes and workarounds

No remediation reported in collected sources.

Missing remediation information is not evidence that no patch exists.

Affected products and versions

Affected products, source version ranges and reporting authorities
ProductVersionsAuthority
monkeytype
monkeytypegame
< 26.43.0 (affected) CNA: GitHub_M

Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.

CVSS assessments

CVSS scores, vectors and reporting authorities
Version / scoreVectorAuthority
3.1 / 9.3
critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:NCNA: GitHub_M

Exploit evidence

References

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