Vulnerability in Python Software Foundation Cpython
CVE-2026-17084
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.
Published · last modified .
EPSS exploit prediction
EPSS: 0.007 (52.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 52nd percentile — 52.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.007 · change: +0.002
Affected products
Weakness classification (CWE)
References
- github.com/python/cpython/pull/155293 (patch)
- github.com/python/cpython/issues/155292 (issue-tracking)
- mail.python.org/archives/list/security-announce@python.org/thread/EUHHTC6EV7HCL… (vendor-advisory)
- af854a3a-2127-422b-91ae-364da2661108
- github.com/python/cpython/commit/7e109d084d55e7eb25837a5f3b47ef9beee547bc (patch)
- github.com/python/cpython/commit/5181304bcec9cfc3c15311741c9154cdff2e3fd7 (patch)
- github.com/python/cpython/commit/1e54caa096678a38afcabecabb1ff72400dd6bae (patch)
- github.com/python/cpython/commit/c016c2535b74227fddf2cf7334dbfead6c930214 (patch)
- github.com/python/cpython/commit/c28b121a4f0b975937c8b5a1b4934bb361d84296 (patch)
- github.com/python/cpython/commit/c42790b34f634051750e5da340d17c7da19e4784 (patch)