SEPTEMBER 14, 2026
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Case File

CVE-2026-81722

HIGH · CVSS 7.5 EPSS 0.36% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-08-27 · Last synced 2026-09-14

CyberRota Analysis

AI-Generated

The nltk PorterStemmer in versions up to 3.10.2 is vulnerable to a denial of service due to inefficient algorithmic complexity in its stemming process, specifically in the _is_consonant() and _measure() functions. This vulnerability allows an attacker to exploit the stemmer with specially crafted tokens, leading to significant CPU resource consumption and potential service unavailability. Organizations using affected versions of nltk should prioritize upgrading to version 3.10.3 or later to mitigate this high-severity risk.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-81722
Severity
HIGH
CVSS
7.5
EPSS
0.36%

Original NVD 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.

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