Python up to 3.15.x stringprep in_table_b2 interpretation conflict

CVSS Meta Temp Score
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CTI Interest Score
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7.0$0-$5k0.43

Summaryinfo

A vulnerability marked as critical has been reported in Python up to 3.15.x. This vulnerability affects the function in_table_b2 of the component stringprep. Performing a manipulation results in input validation. This vulnerability is reported as CVE-2026-17084. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in Python up to 3.15.x. This affects the function in_table_b2 of the component stringprep. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-436. Product A handles inputs or steps differently than Product B, which causes A to perform incorrect actions based on its perception of B's state. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-17084 since 07/24/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.16.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-2924). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Open Source Python

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Interpretation conflict
CWE: CWE-436
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Python 3.16.0

Timelineinfo

07/24/2026 CVE reserved
08/18/2026 +25 days Advisory disclosed
08/18/2026 +0 days VulDB entry created
09/06/2026 +18 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-17084 (🔒)
GCVE (CVE): GCVE-0-2026-17084
GCVE (VulDB): GCVE-100-391647
CERT Bund: WID-SEC-2026-2924 - CPython: Mehrere Schwachstellen

Entryinfo

Created: 08/18/2026 16:14
Updated: 09/06/2026 00:13
Changes: 08/18/2026 16:14 (68), 08/19/2026 21:20 (7), 09/06/2026 00:13 (2)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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