Crossplane signature verification TOCTOU in package manager

Severity: critical · CVSS 9 · Published 2026-06-19

Crossplane is an open-source framework used to manage cloud infrastructure. A security flaw in how it verifies software packages allows a malicious registry to bypass security checks. This could result in the installation of unverified or malicious software onto your infrastructure, potentially leading to a full system compromise or data theft.

Vendors: Crossplane.

Quick answers

Is This vulnerability exploited in the wild?
No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?
Critical severity, with a CVSS score of 9, published 19 June 2026.
Which products and versions are affected?
Crossplane <= 1.21.0-rc.0.
Is there a fix for This vulnerability?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is This vulnerability attacked?
It is attacked over the network, in a software library.
Am I affected?
Check whether you run Crossplane at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A Time-of-Check Time-of-Use (TOCTOU) vulnerability exists in Crossplane's package manager when signature verification is enabled via ImageConfig. When a package is installed using a mutable tag (e.g., a version number) rather than a static digest, Crossplane performs two separate resolution steps: one for signature verification using cosign and another for the actual image pull. A malicious OCI registry can exploit this by serving a valid, signed image during the verification phase and then swapping it for an unsigned, malicious image during the installation phase. This bypasses the security guarantees of signature verification. The fix ensures that the tag is resolved to a digest once and that same digest is used for both verification and fetching.

Affected products

  • Crossplane Crossplane <= 1.21.0-rc.0
  • Crossplane Crossplane >= 2.3.0-rc.0, <= 2.3.2
  • Crossplane Crossplane <= 2.2.2

Timeline

  • 2026-06-16: disclosed: Advisory published to crossplane/crossplane repository
  • 2026-06-19: advisory: GitHub Advisory published and reviewed

References

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