CVE-2026-33540

Aliases:GHSA-3p65-76g6-3w7r
Advisory lineage Upstream: 0 Downstream: 3
Analyzed
Published: 06 Apr 2026, 14:55
Last modified:06 Apr 2026, 15:04

Vulnerability Summary

Overall Risk (default)
medium
40/100
CVSS Score
7.5 HIGH
v3.1 (cve.org)
EPSS Score
0.06% LOW
0% probability 0.00%
KEV
Not listed
Ransomware
No reports
Public exploits
1 found
Dark Web
Not detected

Timeline

06 Apr 2026, 14:55
Published
Vulnerability first disclosed
06 Apr 2026, 15:04
Last Modified
Vulnerability information updated

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.

CVSS Metrics

  • v3.1•HIGH•Score: 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Trends

Current EPSS score: 0.06%• Percentile: 17%

Techniques & Countermeasures

  • CWE-918•Server-Side Request Forgery (SSRF)

    The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Affected Systems

  • distribution_project•distribution

    < 3.1.0

  • distribution•distribution

    < 3.1.0

  • github.com/distribution•distribution

    ≤ 2.8.3

  • github.com/distribution/distribution•v3

    < 3.1.0

References (4)