CVE-2026-15806 `HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching

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 us...

CVE-2026-15806

In Python's urllib.request, HTTPPasswordMgr ignored URL scheme when matching stored credentials, allowing HTTPS credentials to be sent over HTTP if an attacker redirected or downgraded the client, exposing them in cleartext. The fix scopes credential matching by scheme while preserving bare-autho...