Uncontrolled Recursion Affecting nltk package, versions <3.10.3-1


Severity

Recommended
0.0
medium
0
10

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Threat Intelligence

EPSS
0.27% (19th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-NLTK-19385582
  • published28 Aug 2026
  • disclosed27 Aug 2026

Introduced: 27 Aug 2026

NewCVE-2026-81724  (opens in a new tab)
CWE-674  (opens in a new tab)

How to fix?

Upgrade Debian:unstable nltk to version 3.10.3-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream nltk package and not the nltk package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

NLTK before 3.10.3 contains an uncontrolled recursion vulnerability in nltk.featstruct.FeatStructReader that allows unauthenticated attackers to cause a denial of service by supplying deeply nested feature-structure input. Attackers can craft trivial payloads with nested brackets that exceed Python's recursion limit and raise an unhandled RecursionError, crashing applications that parse user-supplied feature structures or feature grammars.

CVSS Base Scores

version 3.1