stringprep.map_table_b2() deviates from RFC 3454 Table B.2
Summary
| CVE | CVE-2026-17084 |
|---|---|
| State | PUBLISHED |
| Assigner | PSF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-08-18 14:16:56 UTC |
| Updated | 2026-08-19 01:16:56 UTC |
| 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. |
Risk And Classification
Primary CVSS: v4.0 6 MEDIUM from [email protected]
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.005110000 probability, percentile 0.414090000 (date 2026-08-19)
Problem Types: CWE-436 | CWE-436 CWE-436 Interpretation Conflict
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 6 | 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/E:X/C... |
| 4.0 | CNA | CVSS | 6 | 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 |
CVSS v4.0 Breakdown
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Python Software Foundation | CPython | affected 3.15.0 python | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/python/cpython/pull/155293 | [email protected] | github.com | |
| www.openwall.com/lists/oss-security/2026/08/18/2 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | |
| github.com/python/cpython/issues/155292 | [email protected] | github.com | |
| github.com/python/cpython/commit/7e109d084d55e7eb25837a5f3b47ef9beee547bc | [email protected] | github.com | |
| mail.python.org/archives/list/[email protected]/thread/EUHHTC6EV7H... | [email protected] | mail.python.org | |
| github.com/python/cpython/commit/5181304bcec9cfc3c15311741c9154cdff2e3fd7 | [email protected] | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Bitshift (https://github.com/TheShiftedBit) (en)
CNA: Seth Larson (https://github.com/sethmlarson) (en)
CNA: Stan Ulbrych (https://github.com/StanFromIreland) (en)
CNA: Marc-Andre Lemburg (https://github.com/malemburg) (en)
CNA: Petr Viktorin (https://github.com/encukou) (en)