CVE-2026-74793: justhtml before 3.11.0 XSS via selectedcontent projection

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 2026-10-12
Weakness: CWE-79

Description

justhtml before 3.11.0 contains a cross-site scripting vulnerability where the default sanitizer bypasses event handler removal in selectedcontent projections. Attackers can inject SVG or MathML elements with event handlers that are cloned and reinserted into output without sanitization, enabling stored or reflected XSS attacks.

Affected products

EmilStenstrom justhtml: before 3.11.0 — fixed in 3.11.0

How to fix

Upgrade to a fixed version: EmilStenstrom justhtml 3.11.0. Check the vendor advisory for mitigations.

References

https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-gjf2-f4jc-69xf
https://www.vulncheck.com/advisories/justhtml-before-xss-via-selectedcontent-projection
https://github.com/EmilStenstrom/justhtml/security/advisories/GHSA-gjf2-f4jc-69xf

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