CVE-2025-0938 MEDIUM

CVE-2025-0938: URL parser allowed square brackets in domain names

Vendor Python Software Foundation
Product CPython
Weakness CWE-20 · Input validation
Published January 31, 2025
Last update April 21, 2026

CVSS base score

6.3/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N

What the vulnerability does

01Description

The Python standard library functions `urllib.parse.urlsplit` and `urlparse` accepted domain names that included square brackets which isn't valid according to RFC 3986. Square brackets are only meant to be used as delimiters for specifying IPv6 and IPvFuture hosts in URLs. This could result in differential parsing across the Python URL parser and other specification-compliant URL parsers.

Key dates

02Disclosure timeline

January 31, 2025 CVE published
April 21, 2026 Record updated