highCVSS 7.5Vulnerability

GHSA-8x48-8g7j-rqxp

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-ww6m-cw3f-q94g. This link is maintained to preserve external references. ## Original Description 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.

Properties

ghsa_id
GHSA-8x48-8g7j-rqxp
severity
high
summary
Duplicate Advisory: Quadratic-time DoS in PorterStemmer via long runs of 'y'
cvss_score
7.5
cve_id
GHSA-8x48-8g7j-rqxp
cvss_vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
is_ghsa_only
true
ghsa_published
2026-08-27T18:32:29Z
source_url
https://github.com/advisories/GHSA-8x48-8g7j-rqxp
ghsa_updated
2026-09-02T14:36:04Z

Related Entities (4)

VULNERABLE_TO (1)

[Software]pip/nltk

AFFECTS (1)

[Software]pip/nltk

HAS_WEAKNESS (1)

[Weakness]Inefficient Algorithmic Complexity

REPORTED_BY (1)

[Source]GitHub Advisory Database

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GHSA-8x48-8g7j-rqxp (CVSS 7.5) — Ninja Signal Threat Intelligence | Ninja Signal