Advisories for Pypi/Soupsieve package

Before tokenizing, selector_iter trims leading/trailing whitespace and comments by running two regexes over the whole raw selector with .search(). The trailing one, RE_WS_END = re.compile(r'{WSC}*$'), is anchored only at the end ($), not the start. Because .search() retries the pattern at every offset, a long run of whitespace or CSS comments that is not sitting exactly at the end of the string makes each retry greedily consume the run and …

soupsieve compiles CSS selector strings with a set of hand-written regular expressions. The shared IDENTIFIER sub-pattern (also embedded in VALUE, and therefore in attribute selectors) places two adjacent quantified groups over overlapping character classes: (?:[classA]|ESC)+(?:[classB]|ESC)*, where both classes match ordinary identifier characters such as a. When a selector contains a long identifier/value run that must ultimately fail to match (e.g. an attribute value with no closing ], or an identifier …

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 css_parser.py enters exponential backtracking. A payload of only 300 bytes causes the regex engine to hang for over 3 seconds, enabling a trivial Regular Expression Denial of Service (ReDoS) attack. To be completely …

The CSS selector parser in soupsieve (the CSS selector engine for Beautiful Soup 4) allocates unbounded memory when compiling large comma-separated selector lists. An attacker who can supply a crafted CSS selector string to soupsieve.compile() or Beautiful Soup's .select() / .select_one() can cause the application to allocate hundreds of megabytes of heap memory from a relatively small input, leading to memory exhaustion and denial of service. To be completely transparent, …