VDB-396280 · CVE-2026-81722 · Nessus 341148

NLTK up to 3.10.2 PorterStemmer PorterStemmer.stem denial of service

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6.3	$0-$5k	0.00

Summaryinfo

A vulnerability labeled as problematic has been found in NLTK up to 3.10.2. Impacted is the function PorterStemmer.stem of the component PorterStemmer. Executing a manipulation can lead to denial of service. This vulnerability is registered as CVE-2026-81722. It is possible to launch the attack remotely. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic was found in NLTK up to 3.10.2. This vulnerability affects the function PorterStemmer.stem of the component PorterStemmer. The manipulation with an unknown input leads to a denial of service vulnerability. The CWE definition for the vulnerability is CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. As an impact it is known to affect availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-81722 since 08/27/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability scanner Nessus provides a plugin with the ID 341148 (Linux Distros Unpatched Vulnerability : CVE-2026-81722), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 3.10.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at CNNVD (CNNVD-2026-98015638) and Tenable (341148). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

NLTK

Version

Website

Product: https://github.com/nltk/nltk/

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (VulnCheck): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Denial of service
CWE: CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 341148
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-81722

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: NLTK 3.10.3

Timelineinfo

08/27/2026 Advisory disclosed
08/27/2026 +0 days CVE reserved
08/27/2026 +0 days VulDB entry created
08/30/2026 +3 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-81722 (🔒)
GCVE (CVE): GCVE-0-2026-81722
GCVE (VulDB): GCVE-100-396280
CNNVD: CNNVD-2026-98015638 - Natural Language Toolkit 资源管理错误漏洞

Entryinfo

Created: 08/27/2026 20:10
Updated: 08/30/2026 20:41
Changes: 08/27/2026 20:10 (76), 08/28/2026 11:22 (2), 08/28/2026 18:17 (6), 08/29/2026 20:08 (1), 08/30/2026 20:41 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.