{"cve":"CVE-2026-33540","nvd":{"published":"2026-04-06T15:17:10.950","modified":"2026-06-17T10:37:40.780","status":"Analyzed","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_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","score":7.5},"cwes":["CWE-918"],"references":["https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r","https://github.com/distribution/distribution/security/advisories/GHSA-3p65-76g6-3w7r"],"products":["distribution_project:distribution"],"source":"nvd","synced_at":"2026-10-19T22:28:59.047572785+00:00"},"epss":{"cve":"CVE-2026-33540","score":0.00274,"percentile":0.19856,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-3p65-76g6-3w7r","url":"https://osv.dev/vulnerability/GHSA-3p65-76g6-3w7r","summary":"Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm","modified":"2026-09-10T03:50:42.426312501Z","packages":[{"ecosystem":"Go","name":"github.com/distribution/distribution/v3","purl":"pkg:golang/github.com/distribution/distribution/v3","ranges":["<3.1.0"],"fixed":["3.1.0"]},{"ecosystem":"Go","name":"github.com/distribution/distribution","purl":"pkg:golang/github.com/distribution/distribution","ranges":["<=2.8.3"],"fixed":[]}]},{"id":"GO-2026-5094","url":"https://osv.dev/vulnerability/GO-2026-5094","summary":"Distribution affected by pull-through cache credential exfiltration via www-authenticate bearer realm in github.com/distribution/distribution","modified":"2026-07-10T01:29:33.422203834Z","packages":[{"ecosystem":"Go","name":"github.com/distribution/distribution","purl":"pkg:golang/github.com/distribution/distribution","ranges":["all versions"],"fixed":[]},{"ecosystem":"Go","name":"github.com/distribution/distribution/v3","purl":"pkg:golang/github.com/distribution/distribution/v3","ranges":["<3.1.0"],"fixed":["3.1.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}