CVE-2026-15806
`HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching
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.
INFO
Published Date :
Aug. 18, 2026, 4:17 p.m.
Last Modified :
Aug. 18, 2026, 6:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-15806
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | MEDIUM | 28c92f92-d60d-412d-b760-e73465c3df22 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update the urllib.request module to the latest version.
- Ensure applications do not request HTTP URLs for authenticated hosts.
- Avoid following redirects to HTTP from HTTPS.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-15806.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-15806 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-15806
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-15806 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-15806 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Aug. 18, 2026
Action Type Old Value New Value Added Reference https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8 Added Reference https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce Added Reference https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce Changed Affected [{'repo': 'https://github.com/python/cpython', 'vendor': 'Python Software Foundation', 'product': 'CPython', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.16.0', 'versionType': 'python'}], 'defaultStatus': 'unaffected'}] [{'repo': 'https://github.com/python/cpython', 'vendor': 'Python Software Foundation', 'product': 'CPython', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.15.0', 'versionType': 'python'}], 'defaultStatus': 'unaffected'}] -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Aug. 18, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/08/18/3 -
New CVE Received by [email protected]
Aug. 18, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/python/cpython', 'vendor': 'Python Software Foundation', 'product': 'CPython', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.16.0', 'versionType': 'python'}], 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 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 Added CWE CWE-319 Added CWE CWE-522 Added Reference https://github.com/python/cpython/issues/155694 Added Reference https://github.com/python/cpython/pull/155696 Added Reference https://mail.python.org/archives/list/[email protected]/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/