CVE-2024-39897 is a medium-severity (CVSS 4.3) CWE-639 vulnerability in zotregistry.io/zot. A fix is available for zotregistry.io/zot — see the affected versions and patch details below.
Cache driver GetBlob() allows read access to any blob without access control check
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2024-39897.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
zotregistry.io/zot🐹zotregistry.dev/zotReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
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() 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() to implement cross repository blob mount (POST /v2/<name>/blobs/uploads/?mount=<digest>&from=<repository name>) 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() too for HEAD /v2/<name>/blobs/<digest>. If a blob is requested that does not exist on the requested repository, Zot will search for it in a global cache (possibly returning a result from an from an incorrect repository) and then will store it into the ImageStore for the requested repository.
RouteHandler.GetBlob() does not call ImageStore.CheckBlob() so it is not directly vulnerable. However an attacker with only limited read access may first call CheckBlob() to fetch the blob from the cache, then call GetBlob() to read the blob.
Mitigation
The attack may be mitigated by configuring "dedupe": false in the "storage" settings. This disables Zot's cache drivers. dedupe is enabled by default using the BoltDB cache driver.
Impact
An attacker can read images that the accessControl policy denies if they have read access to any other second repository.
This attack only allows accessing blobs (both config and layers) by digest. Manifests cannot be accessed.
This attack requires the attacker to know the name of a private image and its layer digests. A scenario where this might happen is if a project has public CI build logs but publishes the image to a private repository. Many image build tools log layer digests.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | zotregistry.io/zot | all versions | 2.1.0go get zotregistry.io/zot@v2.1.0 |
| 🐹Go | zotregistry.dev/zot | all versions | 2.1.0go get zotregistry.dev/zot@v2.1.0 |
Affected Products
zotzotregistryDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for zotregistry.io/zot, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update zotregistry.io/zot to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2024-39897 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2024-39897 in your dependencies?
Find it across Go, including transitive dependencies.