PyPI/nltk CVE-2026-66393: unknown, EPSS 0.52%
NLTK versions before 3.9.4 contain an unbounded recursion vulnerability in JSONTaggedDecoder.decode_obj() that allows attackers to cause denial of service by supplying deeply nested JSON structures. A
Action: Upgrade nltk to 3.9.4 or later.
pip install nltk==3.9.4Affected
| introduced | fixed | last affected |
|---|---|---|
| 0 | 3.9.4 | - |
Fixed versions
| 3.9.4 |
Sources
- osv: PYSEC-2026-3724
- https://www.vulncheck.com/advisories/nltk-before-denial-of-service-via-jsontaggeddecoder
- https://github.com/nltk/nltk/security/advisories/GHSA-rf74-v2fm-23pw
CVE-2026-66393 · published · modified · JSON