GHSA-WW6M-CW3F-Q94G NLTK: Quadratic-time DoS in PorterStemmer via long runs of 'y'

nltk.stem.PorterStemmer.stem -- a ubiquitous public API applied to arbitrary, often untrusted, tokens -- runs in On^2 time on a token containing a long run of the letter 'y', letting a single 20-50 KB token pin a CPU core CWE-407. Root cause isconsonantword, i was made iterative commit for 3633,...

CVE-2026-81722

nltk PorterStemmer in versions = 3.10.2 fixed in 3.10.3 contains an inefficient-algorithmic-complexity denial of service in PorterStemmer.stem. The isconsonant helper walks backward over the entire run of trailing 'y' characters on every call, and measure invokes it for each stem position, causin...