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.

CVSS Vector

References

• https://github.com/nltk/nltk/security/advisories/GHSA-cw6x-m8jw-qmrh
• https://www.vulncheck.com/advisories/nltk-before-3.10.3-denial-of-service-via-uncontrolled-recursion
• https://github.com/nltk/nltk/security/advisories/GHSA-cw6x-m8jw-qmrh