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EUVD-2026-6270

2026-10-06T10:49:01.118866+00:00

EUVD-2026-6270

fkie_cve-2024-39897

2026-10-06T10:49:01.118905+00:00

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.

GHSA-55r9-5mx9-qq7r — Cache driver GetBlob() allows read access to any blob without access control check

2026-10-06T10:49:01.118945+00:00

Affected: Go: zotregistry.io/zot, Go: zotregistry.dev/zot

### Summary

Cache driver `GetBlob()` allows read access to any blob without access control check

### Details

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 allows an attacker to read an image that the `accessControl` policy denies.

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()`.

This cache behavior is intentionally used in [`RouteHandler.CreateBlobUpload()`](https://github.com/project-zot/zot/blob/v2.1.0-rc2/pkg/api/routes.go#L1194-L1197) to implement cross repository blob mount (`POST /v2//blobs/uploads/?mount=&from=`) in Zot. This is still missing an access control to check read access on the source repository.

This cache behavior is unexpectedly also used in [`RouteHandler.CheckBlob()`](https://github.com/project-zot/zot/blob/v2.1.0-rc2/pkg/api/routes.go#L886) too for `HEAD /v2//blobs/`. If a blob is requested that does not…