{"affected":[{"defaultStatus":"unaffected","ecosystem":"pypi","packageName":"nltk","product":"nltk","source":"CNA: VulnCheck","vendor":"nltk","versions":[{"lessThan":"3.10.4","status":"affected","version":"3.6","versionType":"custom"},{"status":"unaffected","version":"3.10.4","versionType":"semver"}]}],"cveId":"CVE-2026-126301","cwes":["CWE-407"],"description":"NLTK from 3.6 before 3.10.4 contains an algorithmic complexity vulnerability in LegalitySyllableTokenizer.tokenize that allows remote attackers to exhaust CPU by supplying long all-vowel tokens. Attackers can submit a token such as a long run of vowels, causing the unguarded onset reversal loop to perform quadratic work and deny service to syllabification components.","epss":null,"exploits":[],"kev":null,"metrics":[{"score":6.9,"severity":"medium","source":"CNA: VulnCheck","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","version":"4.0"},{"score":5.3,"severity":"medium","source":"CNA: VulnCheck","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"},{"score":6.9,"severity":"medium","source":"NVD: disclosure@vulncheck.com","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","version":"4.0"},{"score":5.3,"severity":"medium","source":"NVD: disclosure@vulncheck.com","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}],"modifiedAt":1794565055220,"publishedAt":1794562585223,"references":[{"source":"CNA: VulnCheck","tags":["vendor-advisory"],"url":"https://github.com/nltk/nltk/security/advisories/GHSA-gpwc-27cw-rh9r"},{"source":"CNA: VulnCheck","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/nltk-from-3.6-before-3.10.4-quadratic-cpu-exhaustion-via-legalitysyllabletokenizer-tokenize"},{"source":"disclosure@vulncheck.com","tags":[],"url":"https://github.com/nltk/nltk/security/advisories/GHSA-gpwc-27cw-rh9r"},{"source":"disclosure@vulncheck.com","tags":[],"url":"https://www.vulncheck.com/advisories/nltk-from-3.6-before-3.10.4-quadratic-cpu-exhaustion-via-legalitysyllabletokenizer-tokenize"}],"remediation":[],"revision":"8c7362747b78b0064a1880f00d5a9a897dfbc662bafa33d6f6f6e40bafe92a91","sources":[{"modifiedAt":1794562585223,"name":"CNA: VulnCheck","retrievedAt":1794564585504,"url":"https://www.cve.org/CVERecord?id=CVE-2026-126301"},{"modifiedAt":1794565055220,"name":"NVD","retrievedAt":1794572186088,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-126301"}],"ssvc":null,"status":"published","title":"NLTK from 3.6 before 3.10.4 Quadratic CPU Exhaustion via LegalitySyllableTokenizer.tokenize","updatedAt":1794572186088}