Soup Sieve: Regular Expression Denial of Service (ReDoS) via Selector Parser

SummaryThe CSS selector parser in soupsieve the CSS selector engine for Beautiful Soup 4 contains a regular expression vulnerable to catastrophic backtracking. When processing an attribute selector with an unterminated quoted value, the VALUE regex pattern in cssparser.py enters exponential...

PYSEC-2026-3072 Soup Sieve: Regular Expression Denial of Service (ReDoS) via Selector Parser

Summary The CSS selector parser in soupsieve the CSS selector engine for Beautiful Soup 4 contains a regular expression vulnerable to catastrophic backtracking. When processing an attribute selector with an unterminated quoted value, the VALUE regex pattern in cssparser.py enters exponential...