{"id":"CVE-2026-15806","title":"The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a reque…","summary":"The HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a reque…","severity":"medium","cvss":6,"cvssVector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","cwe":["CWE-319","CWE-522"],"vendor":"Python Software Foundation","product":"CPython","affected":["CPython < 3.12.15","CPython >= 3.13.0 < 3.13.16","CPython >= 3.14.0 < 3.14.8","CPython >= 3.15.0a1 < 3.15.0rc2"],"published":"2026-08-18","updated":"2026-10-01","sourceUpdated":"2026-10-01T01:16:36.283","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-15806","references":[{"url":"https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bcc","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/95355ee3a8e1d3c3d4858d1973aa42a9b91a2801","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce","label":"cna@python.org"},{"url":"https://github.com/python/cpython/commit/dac88d8615078c55f1304ea4c7a2d822700d4e5a","label":"cna@python.org"},{"url":"https://github.com/python/cpython/issues/155694","label":"cna@python.org"},{"url":"https://github.com/python/cpython/pull/155696","label":"cna@python.org"},{"url":"https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/","label":"cna@python.org"},{"url":"http://www.openwall.com/lists/oss-security/2026/08/18/3","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/python/cpython/issues/155694","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd","cve.org","exploit-available"],"exploitAvailable":true,"ssvc":{"exploitation":"poc","automatable":"no","technicalImpact":"partial","timestamp":"2026-08-18T18:56:36.349726Z"},"cvssSource":"cna","epss":0.00451,"epssPercentile":0.36753,"ingestedAt":"2026-09-30T23:29:32.575Z","slug":"CVE-2026-15806","body":"## Overview\n\nThe HTTPPasswordMgr class in the urllib.request module, along with its subclasses HTTPPasswordMgrWithDefaultRealm and HTTPPasswordMgrWithPriorAuth, did not take the URL scheme into account when matching stored credentials against a requested URL. Credentials added for an https:// URL were also used for requests to the same host over http://, so an attacker able to redirect or downgrade a client to plain HTTP (for example, via an HTTPS-to-HTTP redirect or an on-path position) could capture credentials in cleartext. Credentials added for http:// URLs could likewise be sent over https://.\n\nCredential matching is now scoped by URL scheme. Credentials registered with a URL that includes a scheme are only used for requests with the same scheme. Credentials registered with a bare authority (such as example.com or example.com:8080) continue to match any scheme, preserving compatibility with existing code, including proxy authentication.\n\nUsers who cannot upgrade immediately can mitigate by ensuring that applications never make plain http:// requests to hosts for which credentials are registered, for example by not following redirects to http:// URLs.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":45,"depthScoreParts":{"impact":33,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[]}