{"action":"Upgrade nltk to 3.9.4 or later.","affected":[{"fixed":"3.9.4","introduced":"0"}],"component":"nltk","cve_ids":["CVE-2026-66393"],"ecosystem":"PyPI","epss":0.00521,"exploited":false,"fixed_versions":["3.9.4"],"ghsa_id":"GHSA-rf74-v2fm-23pw","id":"tcs_01M5KFXV460F8RNNE3F4E4345M","modified_at":"2026-09-10T03:50:40.818763364Z","published_at":"2026-03-18T20:17:43Z","references":["https://osv.dev/vulnerability/GHSA-rf74-v2fm-23pw","https://github.com/nltk/nltk/security/advisories/GHSA-rf74-v2fm-23pw","https://nvd.nist.gov/vuln/detail/CVE-2026-66393","https://github.com/nltk/nltk/commit/00cdcd392142e6c745e7120c8d50a24127df5fad","https://github.com/nltk/nltk","https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3724.yaml","https://www.vulncheck.com/advisories/nltk-before-denial-of-service-via-jsontaggeddecoder"],"severity":{"label":"medium"},"sources":[{"source":"osv","source_id":"GHSA-rf74-v2fm-23pw","url":"https://osv.dev/vulnerability/GHSA-rf74-v2fm-23pw"}],"summary":"Natural Language Toolkit (NLTK) has unbounded recursion in JSONTaggedDecoder.decode_obj() may cause DoS"}