{"cve":"CVE-2026-81723","nvd":{"published":"2026-08-27T17:21:02.957","modified":"2026-09-24T20:44:42.207","status":"Awaiting Analysis","description":"NLTK versions before 3.10.3 contain a quadratic CPU exhaustion vulnerability in XMLCorpusView._read_xml_fragment() that rescans accumulated XML fragments on every 1 KiB block read. Attackers can provide malformed XML corpus files to cause severe CPU consumption and denial of service through affected readers like BNCCorpusReader.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","score":6.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L","score":3.7},"cwes":["CWE-400"],"references":["https://github.com/nltk/nltk/security/advisories/GHSA-vp2x-qp44-57v7","https://www.vulncheck.com/advisories/nltk-before-3.10.3-quadratic-cpu-exhaustion-via-xmlcorpusview","https://github.com/nltk/nltk/security/advisories/GHSA-vp2x-qp44-57v7"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:50:17.453294893+00:00"},"epss":{"cve":"CVE-2026-81723","score":0.00281,"percentile":0.206,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-vp2x-qp44-57v7","url":"https://osv.dev/vulnerability/GHSA-vp2x-qp44-57v7","summary":"NLTK: Quadratic CPU Exhaustion in `XMLCorpusView._read_xml_fragment()`","modified":"2026-09-10T12:25:42.010688905Z","packages":[{"ecosystem":"PyPI","name":"nltk","purl":"pkg:pypi/nltk","ranges":["<3.10.3"],"fixed":["3.10.3"]}]},{"id":"PYSEC-2026-3871","url":"https://osv.dev/vulnerability/PYSEC-2026-3871","summary":"NLTK: Quadratic CPU Exhaustion in `XMLCorpusView._read_xml_fragment()`","modified":"2026-09-10T12:15:10.959474232Z","packages":[{"ecosystem":"PyPI","name":"nltk","purl":"pkg:pypi/nltk","ranges":["<3.10.3"],"fixed":["3.10.3"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}