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CVE-2026-33540

HIGH CVSS 3.1: 7.5 EPSS 0.04%
Updated Apr 09, 2026
Distribution
Parameter Value
CVSS 7.5 (HIGH)
Affected Versions before 3.1.0
Fixed In 3.1.0
Type CWE-918 (Server-Side Request Forgery (SSRF))
Vendor Distribution
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
None
No data modification
Availability
None
No disruption

CVSS Vector v3.1

Vulnerable Products 1

Configuration From (including) Up to (excluding)
Distribution_Project Distribution
cpe:2.3:a:distribution_project:distribution:*:*:*:*:*:go:*:*
3.1.0

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