CVE-2026-81724

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 v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://github.com/nltk/nltk/security/advisories/GHSA-cw6x-m8jw-qmrh	Exploit Vendor Advisory
https://www.vulncheck.com/advisories/nltk-before-3.10.3-denial-of-service-via-uncontrolled-recursion	Third Party Advisory
https://github.com/nltk/nltk/security/advisories/GHSA-cw6x-m8jw-qmrh	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-08-27 17:21

Updated : 2026-08-31 19:06

NVD link : CVE-2026-81724

Mitre link : CVE-2026-81724

CVE.ORG link : CVE-2026-81724

JSON object : View

Products Affected

nltk

nltk

CWE

CWE-674

Uncontrolled Recursion

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