{"apiVersion":"1.0","identifier":"CVE-2026-5388","description":"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.","publishedAt":"2026-08-23T14:16:53","lastModifiedAt":"2026-08-26T17:17:09","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-5388","cvssScore":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","epssProbability":0.00345,"riskScore":1.01,"affectedProduct":"justhtml","affectedVersions":"<1.15.0","vulnerabilityType":"Library","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-5388","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-5388","en":"https://www.redsauce.net/en/cves/CVE-2026-5388","fr":"https://www.redsauce.net/fr/cves/CVE-2026-5388","pt":"https://www.redsauce.net/pt/cves/CVE-2026-5388","de":"https://www.redsauce.net/de/cves/CVE-2026-5388","sk":"https://www.redsauce.net/sk/cves/CVE-2026-5388","el":"https://www.redsauce.net/el/cves/CVE-2026-5388"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-5388"}}