CVE-2026-81724

Description

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.

Weakness classification

• disclosure@vulncheck.com: CWE-674

Primary references

• disclosure@vulncheck.com — Exploit, Vendor Advisory
• disclosure@vulncheck.com — Third Party Advisory
• 134c704f-9b21-4f2e-91b3-4a467353bcc0 — Exploit, Vendor Advisory