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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2024-39897 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 |
Detection & 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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2024-39897 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2024-39897. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2024-39897 in your dependencies?
O3 Security finds CVE-2024-39897 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.