CVE-2024-39897: Cache driver GetBlob() allows read access to any blob without access control check

Vulnerability summary

CVE-2024-39897 is a medium (CVSS 4.3) vulnerability in project-zot zot. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.3% of scored vulnerabilities.

Timeline

1. 09-07-2024
   PublishedVulnerability first disclosed.
2. 02-08-2024
   Last modifiedVulnerability information updated.

Description

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.

• CWE-639Authorization Bypass Through User-Controlled KeyThe system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.