Inefficient Regular Expression Complexity
The nltk package is vulnerable to ReDoS (regular expression denial of service). An attacker that is able to provide as an input to the _read_comparison_block() function in the file "nltk/corpus/reader/comparative_sents.py" may cause an application to consume an excessive amount of CPU. The vulnerability was fixed on version 3.6.4.
CWE-1333 - Inefficient Regular Expression Complexity
The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.