{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-5388","assignerOrgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","state":"PUBLISHED","assignerShortName":"VulnCheck","dateReserved":"2026-04-01T21:11:10.753Z","datePublished":"2026-08-23T13:34:09.169Z","dateUpdated":"2026-08-26T16:16:10.959Z"},"containers":{"cna":{"providerMetadata":{"orgId":"83251b91-4cc7-4094-a5c7-464a1b83ea10","shortName":"VulnCheck","dateUpdated":"2026-08-23T13:34:09.169Z"},"datePublic":"2026-04-09T00:00:00.000Z","title":"justhtml before 1.15.0 Multiple Security Issues","descriptions":[{"lang":"en","value":"justhtml before 1.15.0 contains multiple security issues in URL sanitization helpers (clean_url_value/clean_url_in_js_string), HTML serialization, Markdown passthrough (html_passthrough=True), and several custom sanitization-policy edge cases. Depending on configuration, an attacker can bypass sanitization to inject active HTML and JavaScript — for example via encoded javascript: URLs, backslash-based relative URLs resolved as remote hosts, markup-breaking programmatic element/attribute names or HTML comments, raw </textarea> reintroduction through Markdown passthrough, or preserved <style>/<meta http-equiv=refresh>/<base href> tags in custom policies. Most custom-policy issues do not affect the default sanitize=True configuration; they primarily affect helper APIs, programmatic DOM construction, html_passthrough=True, and custom policies/transform pipelines."}],"problemTypes":[{"descriptions":[{"lang":"en","description":"Improper Input Validation","cweId":"CWE-20","type":"CWE"}]}],"affected":[{"vendor":"EmilStenstrom","product":"justhtml","defaultStatus":"unaffected","packageURL":"pkg:pypi/justhtml","versions":[{"version":"0","status":"affected","versionType":"semver","lessThan":"1.15.0"},{"version":"1.15.0","status":"unaffected","versionType":"semver"}]}],"metrics":[{"cvssV4_0":{"Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","Safety":"NOT_DEFINED","attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"NETWORK","baseScore":9.3,"baseSeverity":"CRITICAL","exploitMaturity":"NOT_DEFINED","privilegesRequired":"NONE","providerUrgency":"NOT_DEFINED","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","valueDensity":"NOT_DEFINED","vectorString":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"HIGH","vulnConfidentialityImpact":"HIGH","vulnIntegrityImpact":"HIGH","vulnerabilityResponseEffort":"NOT_DEFINED"},"format":"CVSS"},{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"HIGH","baseScore":9.8,"baseSeverity":"CRITICAL","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"format":"CVSS"}],"references":[{"url":"https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-c9vm-hv86-f23r","tags":["vendor-advisory"],"name":"GitHub Security Advisory (GHSA-c9vm-hv86-f23r)"},{"name":"VulnCheck Advisory: justhtml before 1.15.0 Multiple Security Issues","tags":["third-party-advisory"],"url":"https://www.vulncheck.com/advisories/justhtml-before-multiple-security-issues"}],"credits":[{"lang":"en","value":"EmilStenstrom","type":"coordinator"}],"x_generator":{"engine":"vulncheck-endgame"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-26T16:07:56.131062Z","id":"CVE-2026-5388","options":[{"Exploitation":"none"},{"Automatable":"yes"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-08-26T16:16:10.959Z"}}]}}