8.7

GHSA-8X48-8G7J-RQXP: nltk PyPI

CVSS: 8.7v4.0HighPublished
Published 27-08-2026Last modified 10-09-2026
Open JSON

Vulnerability summary

GHSA-8X48-8G7J-RQXP is a high (CVSS 8.7) vulnerability in nltk PyPI.

Overall risk
35/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.7/10
010
High · v4.0 (OSV · Pypi), selected by version preference
EPSS score
Not scored
0%100%
No EPSS score yet
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 1 · Related 1
CVE-2026-81722CGA-4RRW-WX3W-CV46

Timeline

  1. 27-08-2026
    PublishedVulnerability first disclosed.
  2. 10-09-2026
    Last modifiedVulnerability information updated.

Description

Duplicate Advisory: Quadratic-time DoS in PorterStemmer via long runs of 'y' ## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-ww6m-cw3f-q94g.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.

CVSS metrics

2 scores · 1 source · 2 versions

EPSS trend

No EPSS score has been published for this record yet.

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

PyPI1 product
  • nltk≤ 3.10.2

1 vendor · 1 product

References

3 links