Distribution is a toolkit to pack, ship, store, and deliver container content. Prior to 3.1.2, registry/client.(*manifests).Get() reads a manifest returned for a digest-pinned request and passes it to distribution.UnmarshalManifest without hashing the body against the requested digest, allowing a malicious or intercepted registry response to substitute attacker-chosen manifest content even when Docker-Content-Digest claims the requested value. The bundled pull-through proxy in registry/proxy/proxymanifeststore.go can cache and re-serve the substituted manifest. This issue is fixed in version 3.1.2.
https://github.com/distribution/distribution/security/advisories/GHSA-685w-q87j-wqw3
https://github.com/distribution/distribution/releases/tag/v3.1.2
https://github.com/distribution/distribution/commit/960439b09f342cdeb8f1c0e18e8c7349bdcfbf80