CVE-2026-31860 MEDIUM

CVE-2026-31860: Unhead has a XSS bypass in `useHeadSafe` via attribute name injection and case-sensitive protocol check

Vendor Unjs
Product unhead
Weakness CWE-79 · XSS
Published March 12, 2026
Last update March 13, 2026

CVSS base score

5.3/10
Attack vector Network
Attack complexity Low
Privileges required None
User interaction
Confidentiality
Integrity

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

What the vulnerability does

01Description

Unhead is a document head and template manager. Prior to 2.1.11, useHeadSafe() can be bypassed to inject arbitrary HTML attributes, including event handlers, into SSR-rendered <head> tags. This is the composable that Nuxt docs recommend for safely handling user-generated content. The acceptDataAttrs function (safe.ts, line 16-20) allows any property key starting with data- through to the final HTML. It only checks the prefix, not whether the key contains spaces or other characters that break HTML attribute parsing. This vulnerability is fixed in 2.1.11.

Key dates

02Disclosure timeline

March 12, 2026 CVE published
March 13, 2026 Record updated