CVE-2026-17084
stringprep.map_table_b2() deviates from RFC 3454 Table B.2
- State
- Published
- Severity
- 6.0 Medium
- Published
- Aug 18, 2026
- Updated
- Oct 2, 2026
- Reserved
- Jul 24, 2026
Description
The "stringprep" module didn't process characters from RFC 3454 tables B.2 or B.3 correctly: the latest Unicode codepoint attributes were used instead of the specified Unicode 3.2.0. This behavior would cause mismatches when processing domain names using IDNA 2003 (the "idna" codec) and the in_table_b2() function of the "stringprep" module. This only affects domain names containing characters that were not previously registered or had their Unicode attributes such as case-folding behavior updated since Unicode 3.2.0.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 6.0 Medium | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N | PSF |
Weaknesses
- CWE-436 Interpretation Conflict
Affected Products
| Product | Versions |
|---|---|
CPythonPython Software Foundation |
|
References
- https://github.com/python/cpython/pull/155293patch
- https://github.com/python/cpython/issues/155292issue-tracking
- https://mail.python.org/archives/list/security-announce@python.org/thread/EUHHTC6EV7HCLSUHP25C5VHSV4V2MUZN/vendor-advisory
- https://github.com/python/cpython/commit/7e109d084d55e7eb25837a5f3b47ef9beee547bcpatch
- https://github.com/python/cpython/commit/5181304bcec9cfc3c15311741c9154cdff2e3fd7patch
- https://github.com/python/cpython/commit/1e54caa096678a38afcabecabb1ff72400dd6baepatch
- https://github.com/python/cpython/commit/c016c2535b74227fddf2cf7334dbfead6c930214patch
- https://github.com/python/cpython/commit/c28b121a4f0b975937c8b5a1b4934bb361d84296patch
- https://github.com/python/cpython/commit/c42790b34f634051750e5da340d17c7da19e4784patch
- https://github.com/python/cpython/commit/69f92ebaec681e9149dfd70fd02d4ed52d2a6296patch
- https://github.com/python/cpython/commit/d397a4979cfc80a8cd6c73838aa10e9c8cf5ef72patch
- http://www.openwall.com/lists/oss-security/2026/08/18/2
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