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Fencer Vulns
high 7.5

CVE-2026-33540 json

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

published 2026-04-06 7 mo ago modified 2026-09-10 1 mo ago also GHSA-3p65-76g6-3w7r , GO-2026-5094 , EUVD-2026-19289

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 21%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/distribution/distribution/v3 3.1.0
  • distribution_project distribution 3.1.0
  • docker-registry Debian 14 2.8.3+ds1-3

debian advisories DEBIAN-CVE-2026-33540

  • distribution SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 3.1.1-150400.9.41.1

suse advisories SUSE-SU-2026:4212-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
  • distribution openSUSE Tumbleweed 3.1.0-1.1

opensuse advisories openSUSE-SU-2026:21483-1openSUSE-SU-2026:10631-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-33540 updated cvss 3.1

github.com/distribution/distribution: Distribution: Information disclosure via improper validation of authentication realm URL

  • Red Hat OpenShift Container Platform 4 redhat/redhat-operator-index, openshift4/ose-operator-registry, openshift3/ose-operator-lifecycle-manager, openshift4/ose-operator-lifecycle-manager, openshift4/ose-operator-framework-tools-rhel9, openshift4/ose-operator-lifecycle-manager-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Openshift Data Foundation 4.22 odf4/cephcsi-rhel9 1782932114, odf4/odf-cli-rhel9 1783537001, odf4/mcg-core-rhel9 1783536000, odf4/odf-drbd-rhel9 1783537392, odf4/odf-console-rhel9 1783537586, odf4/devicefinder-rhel9 1782932104, +21 more
    fixed: vendor fix RHSA-2026:37387
  • Red Hat Openshift Data Foundation 4.22 odf4/mcg-operator-bundle 1783538986, odf4/ocs-operator-bundle 1783539176, odf4/odf-operator-bundle 1783539513, odf4/cephcsi-operator-bundle 1783538908, odf4/odr-hub-operator-bundle 1783539596, odf4/rook-ceph-operator-bundle 1783539714, +10 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
7 mo ago

Exploit prediction

0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/distribution/distribution/v3
<3.1.0
3.1.0
go github.com/distribution/distribution
<=2.8.3
all versions
 no fix listed

Affected products

  • distribution distribution

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.