CVE-2026-15806 Affecting pypy3 package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published19 Aug 2026
- disclosed18 Aug 2026
Introduced: 18 Aug 2026
NewCVE-2026-15806 (opens in a new tab)How to fix?
There is no fixed version for Debian:unstable pypy3.
NVD Description
Note: Versions mentioned in the description apply only to the upstream pypy3 package and not the pypy3 package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-15806
- https://github.com/python/cpython/pull/155696
- https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/
- https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8
- https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce
- https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce
- http://www.openwall.com/lists/oss-security/2026/08/18/3
- https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6
- https://github.com/python/cpython/commit/851cf9a7142ecbdd39f831055533f58284ad2bcc
- https://github.com/python/cpython/issues/155694