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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2026-15806 Detail

Description

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://. Credential 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. Users 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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

Nist CVSS score does not match with CNA score
CNA:  Python Software Foundation
CVSS-B 6.0 MEDIUM
Vector:  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

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
http://www.openwall.com/lists/oss-security/2026/08/18/3 CVE
https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8 Python Software Foundation
https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce Python Software Foundation
https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce Python Software Foundation
https://github.com/python/cpython/issues/155694 CISA-ADP, Python Software Foundation
https://github.com/python/cpython/pull/155696 Python Software Foundation
https://mail.python.org/archives/list/[email protected]/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/ Python Software Foundation

Weakness Enumeration

CWE-ID CWE Name Source
CWE-319 Cleartext Transmission of Sensitive Information Python Software Foundation  
CWE-522 Insufficiently Protected Credentials Python Software Foundation  

Change History

4 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2026-15806
NVD Published Date:
08/18/2026
NVD Last Modified:
08/18/2026
Source:
Python Software Foundation