CVE-2026-0848 — Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading

Affected: nltk/nltk

NLTK versions <=3.9.2 are vulnerable to arbitrary code execution due to improper input validation in the StanfordSegmenter module. The module dynamically loads external Java .jar files without verification or sandboxing. An attacker can supply or replace the JAR file, enabling the execution of arbitrary Java bytecode at import time. This vulnerability can be exploited through methods such as model poisoning, MITM attacks, or dependency poisoning, leading to remote code execution. The issue arises from the direct execution of the JAR file via subprocess with unvalidated classpath input, allowing malicious classes to execute when loaded by the JVM.

USN-8302-1 — nltk vulnerabilities

Affected: Ubuntu:Pro:14.04:LTS: nltk, Ubuntu:Pro:16.04:LTS: nltk, Ubuntu:Pro:18.04:LTS: nltk, Ubuntu:Pro:20.04:LTS: nltk, Ubuntu:Pro:22.04:LTS: nltk, Ubuntu:Pro:24.04:LTS: nltk, Ubuntu:Pro:26.04:LTS: nltk

It was discovered that NLTK incorrectly validated file paths when opening files using the nltk.util module. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-0846)

It was discovered that NLTK incorrectly validated file paths in multiple CorpusReader classes. An attacker could possibly use this issue to obtain sensitive information. (CVE-2026-0847)

It was discovered that NLTK did not properly validate external Java archive files loaded by StanfordSegmenter. An attacker could possibly use this issue to execute arbitrary code. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, and Ubuntu 26.04 LTS. (CVE-2026-0848)

It was discovered that NLTK's WordNet browser application incorrectly handled user-supplied input. An attacker could possibly use this issue to perform a cross-site scripting attack. (CVE-2026-33230)

It was discovered that NLTK's WordNet browser application did not restrict access to the shutdown endpoint. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-33231)

It was discovered that NLTK's downloader did not validate path attributes in remote XML index files. An attacker could possibly use this issue to create or overwrite arbitrary files. (CVE-2026-33236)

Most recent entries from all

CVE-2026-0848 — Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading

USN-8302-1 — nltk vulnerabilities