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.
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Mon, 06 Apr 2026 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm | |
| Weaknesses | CWE-918 | |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-04-06T15:04:50.154Z
Reserved: 2026-03-20T18:05:11.831Z
Link: CVE-2026-33540
Updated: 2026-04-06T15:04:39.539Z
Status : Received
Published: 2026-04-06T15:17:10.950
Modified: 2026-04-06T16:16:33.873
Link: CVE-2026-33540
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