What’s Vulnerable › Vulnerabilities

CVE-2026-8630: justhtml before 1.12.0 Mutation XSS via Raw Text Elements

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-23 · updated 2026-10-26
• Weakness: CWE-79

Description

justhtml before 1.12.0 (versions <= 1.11.0) contains a mutation cross-site scripting (mXSS) vulnerability in the serialization of raw-text elements such as <style> and <script>. When a DOM tree is processed by sanitize_dom() using a custom policy that keeps these elements, text nodes inside them are serialized literally without escaping, allowing attacker-controlled text containing the matching closing tag sequence to break out of the raw-text context and inject arbitrary HTML into the serialized output. The default sanitization policy is not affected because it drops the contents of style and script.

Affected products

• EmilStenstrom justhtml: before 1.12.0 — fixed in 1.12.0

How to fix

Upgrade to a fixed version: EmilStenstrom justhtml 1.12.0. Check the vendor advisory for mitigations.

References

• https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-qvc2-mg72-jjhx
• https://www.vulncheck.com/advisories/justhtml-before-mutation-xss-via-raw-text-elements

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