Uncontrolled Recursion Affecting nltk package, versions <3.10.0-1


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.36% (30th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-NLTK-19233208
  • published23 Aug 2026
  • disclosed22 Aug 2026

Introduced: 22 Aug 2026

NewCVE-2026-66393  (opens in a new tab)
CWE-674  (opens in a new tab)

How to fix?

Upgrade Debian:unstable nltk to version 3.10.0-1 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 versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decode_obj() that allows attackers to cause denial of service by supplying deeply nested JSON structures. Attackers can craft JSON payloads exceeding the recursion limit to trigger an unhandled RecursionError that crashes the Python process.

CVSS Base Scores

version 3.1