CVE-2026-31860 — MEDIUM (6.1)

Vulnerability 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 Score

6.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

CHANGED

Confidentiality

LOW

Integrity

LOW

Availability

NONE

Affected Products

Vendor	Product	Versions
Unjs	Unhead	< 2.1.11

Related Weaknesses (CWE)

CWE-79

References

https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fvExploitMitigationVendor Advisory
https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fvExploitMitigationVendor Advisory

FAQ

What is CVE-2026-31860?

CVE-2026-31860 is a vulnerability with a CVSS score of 6.1 (MEDIUM). 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...

How severe is CVE-2026-31860?

CVE-2026-31860 has been rated MEDIUM with a CVSS base score of 6.1/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-31860?

Check the references section above for vendor advisories and patch information. Affected products include: Unjs Unhead.