CVE-2026-33540
Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm
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.
| CWE | CWE-918 |
| Vendor | distribution |
| Product | distribution |
| Published | Apr 6, 2026 |
| Last Updated | Apr 6, 2026 |
Get instant alerts for distribution distribution
Be the first to know when new high vulnerabilities affecting distribution distribution are published — delivered to Slack, Telegram or Discord.
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N