Vulnerability · Published Oct 29, 2026 · Assigned by GitHub_M
CVE-2026-118762Monkeytype: fork PR can execute code with elevated GITHUB_TOKEN
Critical 9.3
In plain English
A critical-severity security flaw in monkeytype from monkeytypegame. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| monkeytypegame | monkeytype | < 26.43.0 |
Weakness: CWE-829 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N