CVE-2026-33540
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.
How to fix
- distribution_project distribution3.1.0 or later
- github.com/distribution/distribution/v33.1.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| distribution_project distribution | v < 3.1.0 | 3.1.0 |
| github.com/distribution/distribution/v3Go | v < 3.1.0 | 3.1.0 |
| github.com/distribution/distributionGo | v ≤ 2.8.3, No range specified | — |
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