stringprep.map_table_b2() deviates from RFC 3454 Table B.2

Summary

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.

Timeline

1. Aug 18, 2026, 1:57 PM UTCCVE published
2. Aug 18, 2026, 4:03 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 2, 2026, 12:39 AM UTCRecord last updated

Affected versions

• Python Software Foundation CPython

  fixed in 3.10.22; From 3.11.0 · fixed in 3.11.17; From 3.12.0 · fixed in 3.12.15; From 3.13.0 · fixed in 3.13.16; From 3.14.0 · fixed in 3.14.8; From 3.15.0a1 · fixed in 3.15.0rc2

• libpythonBitnami

  fixed in 3.10.22; From 3.11.0 · fixed in 3.11.17; From 3.12.0 · fixed in 3.12.15; From 3.13.0 · fixed in 3.13.16; From 3.14.0 · fixed in 3.14.8

• pythonBitnami

  fixed in 3.10.22; From 3.11.0 · fixed in 3.11.17; From 3.12.0 · fixed in 3.12.15; From 3.13.0 · fixed in 3.13.16; From 3.14.0 · fixed in 3.14.8

• python-minBitnami

  fixed in 3.10.22; From 3.11.0 · fixed in 3.11.17; From 3.12.0 · fixed in 3.12.15; From 3.13.0 · fixed in 3.13.16; From 3.14.0 · fixed in 3.14.8

References 11