Medium severity · published Mar 12, 2026
CVE-2026-31860
Unhead has a XSS bypass in `useHeadSafe` via attribute name injection and case-sensitive protocol check
6.1
CVSS
0.3%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
Low
Integrity
Low
Availability
None
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 18% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UN
unhead · unjs
< 2.1.11 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-31860
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-31860
Exploit
https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv
More from unhead
6.1
CVE-2026-39315
Unhead has a hasDangerousProtocol() bypass via leading-zero padded HTML entities in useHeadSafe()
6.1
CVE-2026-31873
Unhead has a Bypass of URI Scheme Sanitization in makeTagSafe via Case-Sensitivity