Distribution's token authentication allows attacker to inject an untrusted signing key in a JWT

Vulnerability Description

Distribution is a toolkit to pack, ship, store, and deliver container content. Systems running registry versions 3.0.0-beta.1 through 3.0.0-rc.2 with token authentication enabled may be vulnerable to an issue in which token authentication allows an attacker to inject an untrusted signing key in a JSON web token (JWT). The issue lies in how the JSON web key (JWK) verification is performed. When a JWT contains a JWK header without a certificate chain, the code only checks if the KeyID (`kid`) matches one of the trusted keys, but doesn't verify that the actual key material matches. A fix for the issue is available at commit 5ea9aa028db65ca5665f6af2c20ecf9dc34e5fcd and expected to be a part of version 3.0.0-rc.3. There is no way to work around this issue without patching if the system requires token authentication.

References

• https://github.com/distribution/distribution/security/advisories/GHSA-phw4-mc57-4hwc
• https://github.com/distribution/distribution/commit/f4a500caf68169dccb0b54cb90523e68ee1ac2be