Security Digest · Critical advisory (no CVE assigned)
GHSA-wfqx-gjrf-g28r: Crossplane: Signature verification TOCTOU allows installing unverified package content via mutable tag
Summary Crossplane allows package signature verification to be configured via the ImageConfig mechanism.
CVSS 9.0 Critical GitHub-reviewed · critical
Should you act?
- Only if you depend on one of the packages below, directly or transitively, in a vulnerable version. Check your lockfile with
govulncheck ./.... - No CVE has been assigned, so it will not appear in CVE-based scanners that ignore GitHub advisories.
npm audit,pip-auditand Dependabot do read GitHub advisories.
Affected packages
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Go | github.com/crossplane/crossplane/v2 | >= 2.3.0-rc.0, <= 2.3.2 | 2.3.3 |
| Go | github.com/crossplane/crossplane/v2 | <= 2.2.2 | 2.2.3 |
| Go | github.com/crossplane/crossplane | <= 1.21.0-rc.0 | none listed |
Details
Summary
Crossplane allows package signature verification to be configured via the ImageConfig mechanism. When enabled, the package manager uses cosign to verify that packages are correctly signed before pulling and installing them.
When a package is installed using a tag reference (e.g., a semantic version), a malicious OCI registry could serve a correctly signed image for verification, then subsequently serve an unsigned image for installation. This is possible because Crossplane resolves the tag reference separately for each step.
This vulnerability is relevant only for users who do all three of the following:
1. Configure signature verification for packages, 2. Install packages using tag references rather than digests, and 3. Install packages from registries they do not control.
Mitigation
Installing packages by image digest rather than using tags avoids this issue.
Fix
CVSS: 9.0 (v3.1) CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Sources and references
- GitHub Advisory GHSA-wfqx-gjrf-g28r github.com
- github.com github.com