{"cve":"CVE-2026-5388","nvd":{"published":"2026-08-23T14:16:53.470","modified":"2026-10-12T16:10:00.220","status":"Deferred","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.","cvss_v4":{"vector":"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","score":9.3},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-20"],"references":["https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-c9vm-hv86-f23r","https://www.vulncheck.com/advisories/justhtml-before-multiple-security-issues"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:38.260478770+00:00"},"epss":{"cve":"CVE-2026-5388","score":0.00587,"percentile":0.47789,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-c9vm-hv86-f23r","url":"https://osv.dev/vulnerability/GHSA-c9vm-hv86-f23r","summary":"justhtml includes multiple security fixes","modified":"2026-08-24T03:56:00.144517309Z","packages":[{"ecosystem":"PyPI","name":"justhtml","purl":"pkg:pypi/justhtml","ranges":["<1.15.0"],"fixed":["1.15.0"]}]}],"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."]}