{"id":"BIT-libpython-2026-15806","summary":"`HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching","details":"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 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.","aliases":["BIT-python-2026-15806","BIT-python-min-2026-15806","CVE-2026-15806","PSF-2026-36"],"modified":"2026-08-24T10:25:42.123210722Z","published":"2026-08-24T09:36:56.153Z","database_specific":{"severity":"Medium","cpes":["cpe:2.3:a:python:python:*:*:*:*:*:*:*:*"]},"references":[{"type":"WEB","url":"http://www.openwall.com/lists/oss-security/2026/08/18/3"},{"type":"WEB","url":"https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6"},{"type":"WEB","url":"https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bcc"},{"type":"WEB","url":"https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8"},{"type":"WEB","url":"https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce"},{"type":"WEB","url":"https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce"},{"type":"WEB","url":"https://github.com/python/cpython/issues/155694"},{"type":"WEB","url":"https://github.com/python/cpython/pull/155696"},{"type":"WEB","url":"https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-15806"}],"affected":[{"package":{"name":"libpython","ecosystem":"Bitnami","purl":"pkg:bitnami/libpython"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/libpython/BIT-libpython-2026-15806.json"},"severity":[{"type":"CVSS_V4","score":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X"}]}],"schema_version":"1.9.0"}