Vulnerability Description
Distribution is a toolkit to pack, ship, store, and deliver container content. Prior to 3.1.0, in pull-through cache mode, distribution discovers token auth endpoints by parsing WWW-Authenticate challenges returned by the configured upstream registry. The realm URL from a bearer challenge is used without validating that it matches the upstream registry host. As a result, an attacker-controlled upstream (or an attacker with MitM position to the upstream) can cause distribution to send the configured upstream credentials via basic auth to an attacker-controlled realm URL. This vulnerability is fixed in 3.1.0.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Distribution Project | Distribution | < 3.1.0 |
Related Weaknesses (CWE)
References
- https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-ExploitMitigationVendor Advisory
- https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-ExploitMitigationVendor Advisory
FAQ
What is CVE-2026-33540?
CVE-2026-33540 is a vulnerability with a CVSS score of 7.5 (HIGH). Distribution is a toolkit to pack, ship, store, and deliver container content. Prior to 3.1.0, in pull-through cache mode, distribution discovers token auth endpoints by parsing WWW-Authenticate chall...
How severe is CVE-2026-33540?
CVE-2026-33540 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-33540?
Check the references section above for vendor advisories and patch information. Affected products include: Distribution Project Distribution.