GHSA-QX2G-XRX7-VFH8 NLTK TweetTokenizer vulnerable to denial of service through catastrophic regex backtracking

The URLS regular expression in nltk/tokenize/casual.py, compiled into TweetTokenizer.WORDRE and applied by TweetTokenizer.tokenize, contains a naked-domain branch whose domain-label prefix a-z0-9+?:.-a-z0-9+ is unbounded. Input consisting of many alternating label separators can be partitioned in...

DEBIAN-CVE-2026-72818

The URLS regular expression in nltk/tokenize/casual.py, compiled into TweetTokenizer.WORDRE and applied by TweetTokenizer.tokenize, contains a naked-domain branch whose domain-label prefix a-z0-9+?:.-a-z0-9+ is unbounded. Input consisting of many alternating label separators can be partitioned in...

CVE-2026-72818

NLTK (Python NLP library) is vulnerable to catastrophic regex backtracking in nltk/tokenize/casual.py. The TweetTokenizer.WORD_RE pattern contains an unbounded naked-domain label prefix [a-z0-9]+(?:[.\-][a-z0-9]+)*. Crafted input with many alternating label separators causes the regex engine to e...