This page tracks the Debian fix status. The vulnerability itself is described on the main CVE page. View CVE-2026-81722 →

DEBIAN-CVE-2026-81722

nltk PorterStemmer in versions

Original description

The description as published by the source.

nltk PorterStemmer in versions <= 3.10.2 (fixed in 3.10.3) contains an inefficient-algorithmic-complexity denial of service in PorterStemmer.stem(). The _is_consonant() helper walks backward over the entire run of trailing 'y' characters on every call, and _measure() invokes it for each stem position, causing O(n^2) behavior. A single ~20-50 KB untrusted token consisting of a long run of the letter 'y' followed by a matching suffix (e.g., 'ness') can pin a CPU core for seconds to minutes, causing availability impact.

Source: OSV.dev (Open Source Vulnerabilities) OSV

Affected packages

Debian:12 nltk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]

Debian:13 nltk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]

Debian:14 nltk

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.3-1"}]}]

References

advisory security-tracker.debian.org