Is CVE-2026-81724 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-81724?

CVE-2026-81724 has a CVSS v3 severity of MEDIUM (5.3).

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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.