CVE-2026-5388 evidence review
EmilStenstrom justhtml
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>...
This record remains available for product and version identification, but it is not presented as a complete remediation procedure. Confirm the affected range and the supported fix in a direct vendor advisory before changing production systems.
Identify the product and installed version
Record whether EmilStenstrom justhtml is present, where it is installed, and which interfaces are exposed.
- Record the product name, package or appliance identifier, and installed version.
- Identify internet-facing, administrative, API, and internal access paths.
- Preserve the pre-change configuration and relevant service logs.
Compare the affected range
Use the current record as an identification aid: < 1.15.0. Resolve incomplete inventory results before deciding that an asset is unaffected.
Verify the authoritative remediation source
Open the linked source material and locate a direct vendor advisory for this CVE. Confirm the supported fixed release and product-specific update path before making a production change.
Operational boundary
This page does not replace the vendor advisory, support contract, change-management process, or recovery plan. Do not infer that an asset is unaffected from an incomplete inventory query or a missing fixed-version field.