CVE-2026-39315 Unhead has a hasDangerousProtocol() bypass via leading-zero padded HTML entities in useHeadSafe()

Unhead is a document head and template manager. Prior to 2.1.13, useHeadSafe is the composable that Nuxt's own documentation explicitly recommends for rendering user-supplied content in safely. Internally, the hasDangerousProtocol function in packages/unhead/src/plugins/safe.ts decodes HTML...

CVE-2026-39315

Unhead (document head/template manager) contains a vulnerability in useHeadSafe() where hasDangerousProtocol() decodes HTML entities before blocked-scheme checks. The decoder uses two fixed-width regexes; HTML5 allows leading zeros in numeric character references, and when a padded entity exceeds...

Unhead has XSS bypass in `useHeadSafe` via attribute name injection and case-sensitive protocol check

Summary useHeadSafe can be bypassed to inject arbitrary HTML attributes, including event handlers, into SSR-rendered tags. This is the composable that Nuxt docs recommend for safely handling user-generated content. Details XSS via data- attribute name injection The acceptDataAttrs function safe.t...