The build-pr.yml GitHub workflow is vulnerable to unauthorized modification of the base repository or secrets exfiltration from a Pull Request.
Decathlon/vitamin-web repository
The latest changeset of build-pr.yml to the date.
Workflows triggered on pull_request_target
have read/write tokens for the base repository and the access to secrets. By explicitly checking out and running the build script from a fork the untrusted code is running in an environment that is able to push to the base repository and to access secrets. More details can be found in the article Keeping your GitHub Actions and workflows secure: Preventing pwn requests.
on:
pull_request_target:
types: [opened, synchronize, reopened]
...
- uses: actions/checkout@v2
with:
ref: refs/pull/${{ github.event.number }}/merge
...
- name: Install dependencies
run: yarn install --frozen-lockfile
- name: Build
run: yarn build
The vulnerability allows for unauthorized modification of the base repository and secrets exfiltration.
This issue was discovered and reported by GHSL team member @JarLob (Jaroslav Lobačevski).
You can contact the GHSL team at securitylab@github.com
, please include a reference to GHSL-2021-006
in any communication regarding this issue.