CVE-2026-65915: NLTK before 3.10.0 Arbitrary File Read via FileSystemPathPointer

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-08-22 · updated 2026-10-14
Weakness: CWE-284

Description

NLTK versions before 3.10.0 contain a logic bug in FileSystemPathPointer.open() where the sandbox validation check compares a normalized path against itself, making the security check permanently inert. Attackers can pass file:// URLs to nltk.data.load() to read arbitrary files accessible to the process user, including credentials and configuration files.

Affected products

nltk: before 3.10.0 — fixed in 3.10.0

How to fix

Upgrade to a fixed version: nltk 3.10.0. Check the vendor advisory for mitigations.

References

https://github.com/nltk/nltk/security/advisories/GHSA-72r2-7mfr-5xr9
https://www.vulncheck.com/advisories/nltk-before-arbitrary-file-read-via-filesystempathpointer
https://github.com/nltk/nltk/security/advisories/GHSA-72r2-7mfr-5xr9

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