zot is an OCI image registry. Prior to 2.1.0, the cache driver `GetBlob()` allows read access to any blob without access control check. If a Zot `accessControl` policy allows users read access to some repositories but restricts read access to other repositories and `dedupe` is enabled (it is enabled by default), then an attacker who knows the name of an image and the digest of a blob (that they do not have read access to), they may maliciously read it via a second repository they do have read access to. 
 This attack is possible because [`ImageStore.CheckBlob()` calls `checkCacheBlob()`](https://github.com/project-zot/zot/blob/v2.1.0-rc2/pkg/storage/imagestore/imagestore.go#L1158-L1159) to find the blob a global cache by searching for the digest. If it is found, it is copied to the user requested repository with `copyBlob()`. The attack may be mitigated by configuring "dedupe": false in the "storage" settings. The vulnerability is fixed in 2.1.0.

GitHub, Inc. AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

GitHub, Inc. CWE-639

GitHub, Inc. https://github.com/project-zot/zot/commit/aaee0220e46bdadd12115ac67c19f9d3153eb1df [No types assigned]

GitHub, Inc. https://github.com/project-zot/zot/security/advisories/GHSA-55r9-5mx9-qq7r [No types assigned]