CVE-2026-126304: NLTK 3.10.0 before 3.10.4 Symlink Escape in YCOECorpusReader
NLTK from 3.10.0 before 3.10.4 contains a symlink escape vulnerability in YCOECorpusReader that allows attackers to read files outside the corpus root by planting psd or pos directory symlinks. Attackers controlling a YCOE corpus can make parsedsents() and taggedwords() return file content from other corpora or temporary files within the NLTK data sandbox.
Affected Software
Event History
Frequently Asked Questions
Who is exposed to this issue?
Applications using NLTK versions 3.10.0 through before 3.10.4 are exposed when they process a YCOE corpus controlled by an attacker. The attacker-controlled corpus must be able to contain psd or pos directory symlinks.
What does an attacker need to exploit it?
An attacker needs to control the YCOE corpus being parsed and plant symlinks named as psd or pos directories. No authentication or user interaction is required according to the supplied vector.
What data can be disclosed?
The issue can cause parsed_sents() and tagged_words() to return content from files outside the intended corpus root. The described exposure includes other corpora or temporary files within the NLTK data sandbox.
Which versions should be remediated?
Upgrade NLTK to 3.10.4 or later. Versions from 3.10.0 up to, but not including, 3.10.4 are affected.