CVE-2026-33540

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.

The following products are affected by CVE-2026-33540 vulnerability.

Here, you will find a curated list of external links that provide in-depth information to CVE-2026-33540.

URL	Resource
https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r
https://nvd.nist.gov/vuln/detail/CVE-2026-33540
https://www.cve.org/CVERecord?id=CVE-2026-33540