highVulnerability

GHSA-mf7q-r4rv-jv94

## 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 signature verification and image fetching. This ensures that Crossplane pulls the same content that had its signature verified. The fix has been applied to Crossplane's `main` branch and backported to the v2.3 and v2.2 release branches; it will be released in v2.3.3 and v2.2.3. ## Credits This issue was reported, independently, by @bugbunny-research and @tonghuaroot.

Properties

ghsa_id
GHSA-mf7q-r4rv-jv94
severity
high
summary
Crossplane's TOCTOU between cosign verification and image fetch in xpkg.CachedClient allows tag-based package install to bypass signature check
cve_id
GHSA-mf7q-r4rv-jv94
is_ghsa_only
true
ghsa_published
2026-08-27T17:25:25Z
source_url
https://github.com/advisories/GHSA-mf7q-r4rv-jv94
ghsa_updated
2026-08-27T17:25:26Z

Related Entities (5)

VULNERABLE_TO (1)

[Software]go/github.com/crossplane/crossplane-runtime/v2

AFFECTS (1)

[Software]go/github.com/crossplane/crossplane-runtime/v2

HAS_WEAKNESS (2)

[Weakness]Time-of-check Time-of-use (TOCTOU) Race Condition
[Weakness]Insufficient Verification of Data Authenticity

REPORTED_BY (1)

[Source]GitHub Advisory Database

Explore deeper with Ninja Signal's threat intelligence graph

GHSA-mf7q-r4rv-jv94 — Ninja Signal Threat Intelligence | Ninja Signal