{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "source": "REFERENCES"
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "641be42bb07921ba0f8bffe228b1dc706b092ef6"
            },
            {
              "fixed": "a0d023fbd23773e24b35d8368789470e22cda5d8"
            },
            {
              "fixed": "a2773a34183b7d94a243bb98fd658926cc5348ce"
            },
            {
              "fixed": "a7bb524fef61f77ede01f660ffbd591e1d5837ce"
            }
          ],
          "repo": "https://github.com/python/cpython",
          "type": "GIT"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "PSF",
    "cwe_ids": [
      "CWE-319",
      "CWE-522"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/15xxx/CVE-2026-15806.json",
    "unresolved_ranges": [
      {
        "extracted_events": [
          {
            "fixed": "3.15.0"
          }
        ],
        "source": "AFFECTED_FIELD"
      }
    ]
  },
  "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.",
  "id": "CVE-2026-15806",
  "modified": "2026-08-21T11:30:13.141336352Z",
  "published": "2026-08-18T15:50:57.983Z",
  "references": [
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/08/18/3"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/15xxx/CVE-2026-15806.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15806"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/python/cpython/issues/155694"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bcc"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce"
    },
    {
      "type": "FIX",
      "url": "https://github.com/python/cpython/pull/155696"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/python/cpython"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "`HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching"
}