CVE-2026-15806

NameCVE-2026-15806
DescriptionThe 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.
SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
pypy3 (PTS)bookworm7.3.11+dfsg-2+deb12u3vulnerable
trixie7.3.19+dfsg-2vulnerable
forky, sid7.3.23+dfsg-1vulnerable
python3.11 (PTS)bookworm3.11.2-6+deb12u8vulnerable
bookworm (security)3.11.2-6+deb12u3vulnerable
python3.13 (PTS)trixie3.13.5-2+deb13u3vulnerable
forky, sid3.13.15-1vulnerable
python3.14 (PTS)forky3.14.7-1vulnerable
sid3.14.7-3fixed
python3.15 (PTS)forky3.15.0~rc1-1vulnerable
sid3.15.0~rc2-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pypy3source(unstable)(unfixed)
python2.7sourcebullseye(unfixed)end-of-life
python2.7source(unstable)(unfixed)
python3.11source(unstable)(unfixed)
python3.13source(unstable)(unfixed)
python3.14source(unstable)3.14.7-3
python3.15source(unstable)3.15.0~rc2-1
python3.9source(unstable)(unfixed)

Notes

[trixie] - python3.13 <no-dsa> (Minor issue)
[bullseye] - python2.7 <end-of-life> (EOL in bullseye LTS)
[trixie] - pypy3 <no-dsa> (Minor issue)
[bookworm] - pypy3 <postponed> (Minor issue)
https://mail.python.org/archives/list/security-announce@python.org/thread/3OKPE5S75KDNA7FY7AI3PL2MXM2X5RB3/
https://github.com/python/cpython/issues/155694
https://github.com/python/cpython/pull/155696
Fixed by: https://github.com/python/cpython/commit/a7bb524fef61f77ede01f660ffbd591e1d5837ce (main)
Fixed by: https://github.com/python/cpython/commit/641be42bb07921ba0f8bffe228b1dc706b092ef6 (v3.15.0rc2)
Fixed by: https://github.com/python/cpython/commit/a0d023fbd23773e24b35d8368789470e22cda5d8 (3.14 branch)
Fixed by: https://github.com/python/cpython/commit/a2773a34183b7d94a243bb98fd658926cc5348ce (3.13 branch)

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