CVE-2023-31128 – NextCloud Cookbook's pull-checks.yml workflow is vulnerable to OS Command Injection

https://notcve.org/view.php?id=CVE-2023-31128

NextCloud Cookbook is a recipe library app. Prior to commit a46d9855 on the `master` branch and commit 489bb744 on the `main-0.9.x` branch, the `pull-checks.yml` workflow is vulnerable to command injection attacks because of using an untrusted `github.head_ref` field. The `github.head_ref` value is an attacker-controlled value. Assigning the value to `zzz";echo${IFS}"hello";#` can lead to command injection. Since the permission is not restricted, the attacker has a write-access to the repository. • https://github.com/nextcloud/cookbook/blob/a14d6ffc4d45e1447556f68606129dfd6c1505cf/.github/workflows/pull-checks.yml#L67 https://github.com/nextcloud/cookbook/commit/489bb744 https://github.com/nextcloud/cookbook/commit/a46d98559e2c64292da9ffb06138cccc2e50ae1b https://github.com/nextcloud/cookbook/security/advisories/GHSA-c5pc-mf2f-xq8h https://securitylab.github.com/research/github-actions-untrusted-input • CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') •