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CVE-2026-33540

NVD

https://nvd.nist.gov/vuln/detail/CVE-2026-33540

Severity

7.5

High

CVSS V3

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Summary

Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm

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.

References

Affected packages

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