CVSS 4.0
6.9 mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NCVE-2026-81724
Medium (6.9) in nltk nltk. EPSS 0.5% chance of exploitation in the next 30 days. Fixed in nltk 3.10.3.
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.
Severity
CVSS 3.1
5.3 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- EPSS
- 0.5% chance of exploitation in the next 30 days; higher than 39% of CVEs (scores of 2026-10-31)
- CWE
- CWE-674
- Published
- Modified
- Record from
- the NVD, synced
Affected
- nltk:nltk
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-cw6x-m8jw-qmrh | PyPI | nltk | <3.10.3 | 3.10.3 |
| PYSEC-2026-3739 | PyPI | nltk | <3.10.3 | 3.10.3 |