CVE-2026-12199
Description
A flaw was found in the nltk component, specifically in the nltk.app.wordnet_app. An unauthenticated remote attacker can exploit this vulnerability by sending a specially crafted GET request to the WordNet Browser HTTP server when it is running in its default mode. This allows the attacker to immediately shut down the server, leading to a denial of service (DoS) and impacting service availability. The issue stems from insufficient authentication and protection mechanisms for critical server functions.
Statement
A flaw was found in NLTK's WordNet Browser HTTP server. When started in its default mode, the server listens on all interfaces and processes a specific unauthenticated GET request to terminate the process immediately, resulting in a denial of service. The WordNet Browser is a development/research tool and is not typically deployed in production environments.
Mitigation
Do not expose the NLTK WordNet Browser HTTP server to untrusted networks. Bind the server to localhost only if it must be used. Upgrade to NLTK version 3.9.4 or later when available.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 7.5 |
| Attack Vector | Adjacent Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Red Hat CVSS v3 Score Explanation
Adjusted from AV:N to AV:A — WordNet Browser server is never started in RH products; if started, reachable only from adjacent pod network in OCP/K8s, not externally.
Understanding the Weakness (CWE)
Access Control,Other
Technical Impact: Gain Privileges or Assume Identity; Varies by Context
Exposing critical functionality essentially provides an attacker with the privilege level of that functionality. The consequences will depend on the associated functionality, but they can range from reading or modifying sensitive data, accessing administrative or other privileged functionality, or possibly even executing arbitrary code.
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