Crossplane: Signature verification TOCTOU allows installing unverified package content via mutable tag

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

9.0 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

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 The package manager has been updated to resolve tag references once and use the resulting digest for both…

Published by the source

19 Jun 2026, 20:47 UTC

Last modified by the source

29 Sep 2026, 21:17 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-wfqx-gjrf-g28r

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# Patch Next advisory brief: GHSA-wfqx-gjrf-g28r

Advisory: Crossplane: Signature verification TOCTOU allows installing unverified package content via mutable tag
IDs: GHSA-wfqx-gjrf-g28r
Record: https://patchnext.com/advisories/ghsa-wfqx-gjrf-g28r (revision 1, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Critical (CVSS 9.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/crossplane/crossplane/v2 2.3.3, 2.2.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/crossplane/crossplane: affected <= 1.21.0-rc.0
- Go github.com/crossplane/crossplane/v2: affected >= 2.3.0-rc.0, <= 2.3.2; <= 2.2.2; fixed in 2.3.3, 2.2.3

## Suggested inspection (read-only)
- Go github.com/crossplane/crossplane: check the installed version with your package manager.
- Go github.com/crossplane/crossplane/v2: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/crossplane/crossplane, github.com/crossplane/crossplane/v2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-wfqx-gjrf-g28r (GitHub-reviewed advisory GHSA-wfqx-gjrf-g28r lists affected ranges: Go github.com/crossplane/crossplane/v2 >=2.3.0-rc.0 =0 =0 <=1.21.0-rc.0)

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