{"id":"GHSA-cr32-g25g-vxjj","summary":"showdown metadata title handling allows cross-site scripting","details":"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.","aliases":["CVE-2026-59711"],"modified":"2026-08-07T21:26:12.357138Z","published":"2026-07-06T21:30:43Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2026-08-07T21:05:38Z","nvd_published_at":"2026-07-06T21:16:58Z","cwe_ids":["CWE-79"],"severity":"MODERATE"},"references":[{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59711"},{"type":"WEB","url":"https://github.com/showdownjs/showdown/issues/1047"},{"type":"WEB","url":"https://github.com/showdownjs/showdown/commit/184a3e4e97f90e075c4512f2c4c06dcf655e91b7"},{"type":"PACKAGE","url":"https://github.com/showdownjs/showdown"},{"type":"WEB","url":"https://www.vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument"}],"affected":[{"package":{"name":"showdown","ecosystem":"npm","purl":"pkg:npm/showdown"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"last_affected":"2.1.0"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-cr32-g25g-vxjj/GHSA-cr32-g25g-vxjj.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"CVSS_V4","score":"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"}]}