---
cve: "CVE-2026-81722"
severity: "HIGH"
cvss: 7.5
epss: "27.9%"
vendor: "Generic Security"
kev: false
exploited: false
published: "2026-08-27 17:21:02"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-04T17:43:54+02:00"
---

# CVE-2026-81722

> 7.5 HIGH

## Beschreibung

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-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- 303f6e2ba8e4548a5f54fd65d86bb5c9a949f1db (Commit)

## Referenzen

- <https://github.com/nltk/nltk/security/advisories/GHSA-ww6m-cw3f-q94g>
- <https://www.vulncheck.com/advisories/nltk-porterstemmer-before-3.10.3-quadratic-time-dos>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-81722) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_