{"id":"CVE-2026-59711","state":"PUBLISHED","title":"showdown - Cross-Site Scripting via Unescaped Metadata Title in completeHTMLDocument","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.","publishedAt":"2026-07-06T21:00:38.491Z","updatedAt":"2026-07-07T14:06:55.895Z","severity":{"score":5.3,"label":"Medium","version":"4.0","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","source":"VulnCheck"},"assigner":"VulnCheck","products":["showdown showdown"],"affected":[{"vendor":"showdown","product":"showdown","packageURL":"pkg:npm/showdown","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"2.1.0","versionType":"semver"}]}],"references":["https://github.com/showdownjs/showdown/issues/1047","https://github.com/showdownjs/showdown","https://www.vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument"],"weaknesses":["CWE-79"],"ingestedAt":"2026-10-29T20:12:32.778Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/59xxx/CVE-2026-59711.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-59711","state":"PUBLISHED","datePublished":"2026-07-06T21:00:38.491Z","dateUpdated":"2026-07-07T14:06:55.895Z","assignerShortName":"VulnCheck","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateReserved":"2026-07-06T15:31:46.188Z"},"containers":{"cna":{"title":"showdown - Cross-Site Scripting via Unescaped Metadata Title in completeHTMLDocument","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"showdown","product":"showdown","packageURL":"pkg:npm/showdown","defaultStatus":"unaffected","versions":[{"version":"0","status":"affected","lessThanOrEqual":"2.1.0","versionType":"semver"}]}],"references":[{"url":"https://github.com/showdownjs/showdown/issues/1047","name":"GitHub Issue","tags":["issue-tracking"]},{"url":"https://github.com/showdownjs/showdown","name":"Product","tags":["product"]},{"url":"https://www.vulncheck.com/advisories/showdown-cross-site-scripting-via-unescaped-metadata-title-in-completehtmldocument","tags":["third-party-advisory"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"NONE","privilegesRequired":"NONE","userInteraction":"PASSIVE","vulnConfidentialityImpact":"LOW","subConfidentialityImpact":"LOW","vulnIntegrityImpact":"LOW","subIntegrityImpact":"LOW","vulnAvailabilityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"MEDIUM","baseScore":5.3,"vectorString":"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"}},{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"REQUIRED","scope":"CHANGED","confidentialityImpact":"LOW","integrityImpact":"LOW","availabilityImpact":"NONE","version":"3.1","baseSeverity":"MEDIUM","baseScore":6.1,"vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-79","lang":"en","description":"Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')","type":"CWE"}]}],"providerMetadata":{"shortName":"VulnCheck","orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","dateUpdated":"2026-07-07T13:48:12.383Z"},"datePublic":"2026-03-12T00:00:00.000Z","cpeApplicability":[{"nodes":[{"operator":"OR","cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:a:showdownjs:showdown:*:*:*:*:*:node.js:*:*","versionEndExcluding":"*"}]}]}],"credits":[{"lang":"en","value":"Scott Moore - VulnCheck","type":"reporter"}],"x_generator":{"engine":"vulncheck-endgame"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/showdownjs/showdown/issues/1047","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-07T14:06:48.974766Z","id":"CVE-2026-59711","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-07T14:06:55.895Z"}}]}}}