7.5

CVE-2026-33540: Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm

Analyzed
AliasesUBUNTU-CVE-2026-33540DEBIAN-CVE-2026-33540CGA-26q6-c78h-8g8j
Published 06-04-2026Last modified 06-04-2026

Vulnerability summary

CVE-2026-33540 is a high (CVSS 7.5) Server-Side Request Forgery vulnerability in distribution_project distribution. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 21% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Prioritisepublic exploit

Public exploit (GitHub, Date unknown)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.29%
0%100%
Low · -0.10 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1github

Advisory lineage

Upstream 0 · Downstream 3 · Related 4
OPENSUSE-SU-2026:10631-1OPENSUSE-SU-2026:21483-1SUSE-SU-2026:4212-1CGA-4FXM-PMFG-6HJW

Timeline

  1. 06-04-2026
    PublishedVulnerability first disclosed.
  2. 06-04-2026
    Last modifiedVulnerability 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

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.29%

Chance of exploitation in the next 30 days

Percentile

21%

Versus all other CVEs

30-day change

Decrease -0.10 pp

From 0.39% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • githubUnverified

    Distribution

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard65 products
  • argocd-image-updater< 1.3.0-r0
  • argocd-image-updater-fips< 1.3.0-r0
  • envoy-gateway-egctl< 1.7.1-r3
  • envoy-gateway-fips-egctl< 1.7.1-r3
  • gitlab-rails-ce-18.1All versions (No fix recorded)
Wolfi10 products
  • argocd-image-updater< 1.3.0-r0
  • envoy-gateway-egctl< 1.7.1-r3
  • gitness< 3.3.0-r12
  • harbor-2.14All versions (No fix recorded)
  • harbor-2.14-exporterAll versions (No fix recorded)
Debian1 product
  • docker-registryAll versions (No fix recorded) | < 2.8.3+ds1-3
Distribution1 product
Distribution_project1 product
Github.com/distribution1 product
  • distribution≤ 2.8.3 | All versions (No fix recorded)
Github.com/distribution/distribution1 product
  • v3< 3.1.0
Ubuntu1 product
  • docker-registryAll versions (No fix recorded)

8 vendors · 81 products

References

8 links