Cross-site scripting via HTML sanitization bypasses
Published Aug 23, 2026 · Updated Aug 23, 2026
HTML sanitization bypasses in JustHTML before 1.16.0 allow remote attackers to preserve active markup in sanitized output. The sanitizer retains stale compiled policies after nested policy mutation, mishandles mixed-case or namespace-confused programmatic DOM nodes, and serializes crafted doctypes into executable markup. Exploitation requires an application to render the result and generally use programmatic DOM input, reused or custom policies, or other advanced paths; ordinary parsed HTML with default sanitization is largely unaffected.
Summary
What happened
HTML sanitization bypasses in JustHTML before 1.16.0 allow remote attackers to preserve active markup in sanitized output. The sanitizer retains stale compiled policies after nested policy mutation, mishandles mixed-case or namespace-confused programmatic DOM nodes, and serializes crafted doctypes into executable markup. Exploitation requires an application to render the result and generally use programmatic DOM input, reused or custom policies, or other advanced paths; ordinary parsed HTML with default sanitization is largely unaffected.
The record
- CVE
- CVE-2026-7808
- Published
- Aug 23, 2026
- Updated
- Aug 23, 2026
- Vendor
- Emil Stenström
- Product
- JustHTML
- Classifications
- CWE-20, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 23, 2026CVE publishedPublication date reported by the CVE source.
- Aug 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.16.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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