{"cve":"CVE-2026-59711","nvd":{"published":"2026-07-06T21:16:58.660","modified":"2026-10-25T20:10:00.147","status":"Deferred","description":"showdown contains a cross-site scripting vulnerability in metadata title handling that allows attackers to inject arbitrary HTML and JavaScript. When completeHTMLDocument option is enabled, unescaped less-than and greater-than characters in markdown frontmatter metadata are inserted directly into HTML title tags, enabling attackers to break out of the title context and execute malicious scripts in the rendered page.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N","score":5.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1},"cwes":["CWE-79"],"references":["https://github.com/showdownjs/showdown","https://github.com/showdownjs/showdown/issues/1047","https://www.vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument","https://github.com/showdownjs/showdown/issues/1047"],"products":[],"source":"nvd","synced_at":"2026-10-25T23:44:34.550481224+00:00"},"epss":{"cve":"CVE-2026-59711","score":0.00327,"percentile":0.25543,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-cr32-g25g-vxjj","url":"https://osv.dev/vulnerability/GHSA-cr32-g25g-vxjj","summary":"showdown metadata title handling allows cross-site scripting","modified":"2026-09-10T03:51:11.523533669Z","packages":[{"ecosystem":"npm","name":"showdown","purl":"pkg:npm/showdown","ranges":["<=2.1.0"],"fixed":[]}]}],"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."]}