cal.com (calcom repository, later renamed cal.diy) is affected by a repository takeover vulnerability in its GitHub Actions workflows. The workflow pr.yml uses the pull_request_target trigger with the repository's default write permissions and passes them down to check-types.yml. check-types.yml then performs a 'dangerous' checkout of the attacker-submitted pull request code (via the dangerous-git-checkout action) and subsequently executes it (through yarn install and package.json scripts). An attacker can open a pull request whose code runs arbitrary commands with the repository's write-scoped GITHUB_TOKEN, allowing them to push commits, merge or mutate pull requests, add or delete comments, and delete or force-push branches, thereby compromising the repository. The main branch is affected; no patched version is available.
https://www.vulncheck.com/advisories/cal-com-repository-takeover-via-pull-request-target-workflow
https://github.com/calcom/cal.diy/security/advisories/GHSA-p3f6-52gv-cj7m
https://github.com/calcom/cal.diy/commit/9aa60fae41a6b6b101c86bf430754b439f440871
Published: 2026-07-23
Updated: 2026-07-24
Base Score: 8.7
Vector: CVSS2#AV:N/AC:L/Au:S/C:P/I:C/A:C
Severity: High
Base Score: 9.9
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:H
Severity: Critical
Base Score: 8.5
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:H/SC:L/SI:H/SA:H
Severity: High
EPSS: 0.00386