Vulnerability-Lookup

CVE-2026-31860 (GCVE-0-2026-31860)

Vulnerability from cvelistv5 – Published: 2026-03-12 17:18 – Updated: 2026-03-13 16:26

Title

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

Summary

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.

Severity ?

5.3 (Medium)


                        
                          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

CWE

CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Assigner

GitHub_M

References

URL

Tags

https://github.com/unjs/unhead/security/advisorie…

x_refsource_CONFIRM

Impacted products

	Vendor	Product	Version
	unjs	unhead	Affected: < 2.1.11

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-31860",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-13T16:26:47.686961Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-13T16:26:51.670Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "unhead",
          "vendor": "unjs",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.1.11"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "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 \u003chead\u003e 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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "LOW",
            "subIntegrityImpact": "LOW",
            "userInteraction": "PASSIVE",
            "vectorString": "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-79",
              "description": "CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-12T17:18:20.452Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv"
        }
      ],
      "source": {
        "advisory": "GHSA-g5xx-pwrp-g3fv",
        "discovery": "UNKNOWN"
      },
      "title": "Unhead has a XSS bypass in `useHeadSafe` via attribute name injection and case-sensitive protocol check"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-31860",
    "datePublished": "2026-03-12T17:18:20.452Z",
    "dateReserved": "2026-03-09T19:02:25.012Z",
    "dateUpdated": "2026-03-13T16:26:51.670Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-31860",
      "date": "2026-04-23",
      "epss": "0.00017",
      "percentile": "0.04238"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-31860\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-03-12T18:16:24.227\",\"lastModified\":\"2026-03-16T17:56:34.140\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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 \u003chead\u003e 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.\"},{\"lang\":\"es\",\"value\":\"Unhead es un gestor de cabecera de documento y plantillas. Antes de la 2.1.11, se puede eludir useHeadSafe() para inyectar atributos HTML arbitrarios, incluyendo manejadores de eventos, en etiquetas  renderizadas por SSR. Este es el composable que la documentaci\u00f3n de Nuxt recomienda para manejar de forma segura contenido generado por el usuario. La funci\u00f3n acceptDataAttrs (safe.ts, l\u00ednea 16-20) permite cualquier clave de propiedad que comience con \u0027data-\u0027 hasta el HTML final. Solo verifica el prefijo, no si la clave contiene espacios u otros caracteres que rompen el an\u00e1lisis de atributos HTML. Esta vulnerabilidad est\u00e1 corregida en la 2.1.11.\"}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"PASSIVE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"NONE\",\"subConfidentialityImpact\":\"LOW\",\"subIntegrityImpact\":\"LOW\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}],\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N\",\"baseScore\":6.1,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.8,\"impactScore\":2.7}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-79\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:unjs:unhead:*:*:*:*:*:*:*:*\",\"versionEndExcluding\":\"2.1.11\",\"matchCriteriaId\":\"67F3AFEA-7DE2-46CC-AC50-D8B49F57C37E\"}]}]}],\"references\":[{\"url\":\"https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv\",\"source\":\"security-advisories@github.com\",\"tags\":[\"Exploit\",\"Mitigation\",\"Vendor Advisory\"]},{\"url\":\"https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv\",\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"tags\":[\"Exploit\",\"Mitigation\",\"Vendor Advisory\"]}]}}",
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-31860\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-03-13T16:26:47.686961Z\"}}}], \"references\": [{\"url\": \"https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-03-13T16:26:40.074Z\"}}], \"cna\": {\"title\": \"Unhead has a XSS bypass in `useHeadSafe` via attribute name injection and case-sensitive protocol check\", \"source\": {\"advisory\": \"GHSA-g5xx-pwrp-g3fv\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV4_0\": {\"version\": \"4.0\", \"baseScore\": 5.3, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"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\", \"userInteraction\": \"PASSIVE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"NONE\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"LOW\", \"vulnIntegrityImpact\": \"NONE\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"LOW\", \"vulnConfidentialityImpact\": \"NONE\"}}], \"affected\": [{\"vendor\": \"unjs\", \"product\": \"unhead\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003c 2.1.11\"}]}], \"references\": [{\"url\": \"https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv\", \"name\": \"https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv\", \"tags\": [\"x_refsource_CONFIRM\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"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 \u003chead\u003e 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.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-79\", \"description\": \"CWE-79: Improper Neutralization of Input During Web Page Generation (\u0027Cross-site Scripting\u0027)\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-03-12T17:18:20.452Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-31860\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-03-13T16:26:51.670Z\", \"dateReserved\": \"2026-03-09T19:02:25.012Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-03-12T17:18:20.452Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

GHSA-G5XX-PWRP-G3FV

Vulnerability from github – Published: 2026-03-12 14:19 – Updated: 2026-03-12 19:14

Summary

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

Details

Summary

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.

Details

XSS via data-* attribute name injection

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.

function acceptDataAttrs(value: Record<string, string>) {
  return Object.fromEntries(
    Object.entries(value || {}).filter(([key]) => key === 'id' || key.startsWith('data-')),
  )
}

This result gets merged into every tag's props at line 114:

tag.props = { ...acceptDataAttrs(prev), ...next }

Then propsToString (propsToString.ts, line 26) interpolates property keys directly into the HTML string with no sanitization:

attrs += value === true ? ` ${key}` : ` ${key}="${encodeAttribute(value)}"`

A space in the key breaks out of the attribute name. Everything after the space becomes separate HTML attributes.

PoC

The most practical vector uses a link tag. <link rel="stylesheet"> fires onload once the stylesheet loads, giving reliable script execution:

useHeadSafe({
  link: [{
    rel: 'stylesheet',
    href: '/valid-stylesheet.css',
    'data-x onload=alert(document.domain) y': 'z'
  }]
})

SSR output:

<link data-x onload=alert(document.domain) y="z" rel="stylesheet" href="/valid-stylesheet.css">

The browser parses onload=alert(document.domain) as its own attribute. Once the stylesheet loads, the handler fires.

The same injection works on any tag type since acceptDataAttrs is applied to all of them at line 114. Here's the same thing on a meta tag (the injected attributes render, though onclick doesn't fire on non-interactive <meta> elements):

useHeadSafe({
  meta: [{
    name: 'description',
    content: 'legitimate content',
    'data-x onclick=alert(document.domain) y': 'z'
  }]
})

Realistic scenario

A Nuxt app accepts SEO metadata from a CMS or user profile. The developer uses useHeadSafe() as the docs recommend. An attacker puts a data-* key with spaces and an event handler into their input. The payload renders into the HTML on every page load.

Suggested fix

For vulnerability 1, validate that attribute names only contain characters legal in HTML attributes:

const SAFE_ATTR_RE = /^[a-zA-Z][a-zA-Z0-9\-]*$/

function acceptDataAttrs(value: Record<string, string>) {
  return Object.fromEntries(
    Object.entries(value || {}).filter(
      ([key]) => (key === 'id' || key.startsWith('data-')) && SAFE_ATTR_RE.test(key)
    ),
  )
}

Severity ?

5.3 (Medium)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.1.10"
      },
      "package": {
        "ecosystem": "npm",
        "name": "unhead"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.1.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-31860"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-79"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-12T14:19:15Z",
    "nvd_published_at": "2026-03-12T18:16:24Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\n`useHeadSafe()` can be bypassed to inject arbitrary HTML attributes, including event handlers, into SSR-rendered `\u003chead\u003e` tags. This is the composable that Nuxt docs recommend for safely handling user-generated content.\n\n## Details\n\n**XSS via `data-*` attribute name injection**\n\nThe `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.\n\n```typescript\nfunction acceptDataAttrs(value: Record\u003cstring, string\u003e) {\n  return Object.fromEntries(\n    Object.entries(value || {}).filter(([key]) =\u003e key === \u0027id\u0027 || key.startsWith(\u0027data-\u0027)),\n  )\n}\n```\n\nThis result gets merged into every tag\u0027s props at line 114:\n\n```typescript\ntag.props = { ...acceptDataAttrs(prev), ...next }\n```\n\nThen `propsToString` (propsToString.ts, line 26) interpolates property keys directly into the HTML string with no sanitization:\n\n```typescript\nattrs += value === true ? ` ${key}` : ` ${key}=\"${encodeAttribute(value)}\"`\n```\n\nA space in the key breaks out of the attribute name. Everything after the space becomes separate HTML attributes.\n\n### PoC\n\nThe most practical vector uses a `link` tag. `\u003clink rel=\"stylesheet\"\u003e` fires `onload` once the stylesheet loads, giving reliable script execution:\n\n```javascript\nuseHeadSafe({\n  link: [{\n    rel: \u0027stylesheet\u0027,\n    href: \u0027/valid-stylesheet.css\u0027,\n    \u0027data-x onload=alert(document.domain) y\u0027: \u0027z\u0027\n  }]\n})\n```\n\nSSR output:\n\n```html\n\u003clink data-x onload=alert(document.domain) y=\"z\" rel=\"stylesheet\" href=\"/valid-stylesheet.css\"\u003e\n```\n\nThe browser parses `onload=alert(document.domain)` as its own attribute. Once the stylesheet loads, the handler fires.\n\nThe same injection works on any tag type since `acceptDataAttrs` is applied to all of them at line 114. Here\u0027s the same thing on a `meta` tag (the injected attributes render, though `onclick` doesn\u0027t fire on non-interactive `\u003cmeta\u003e` elements):\n\n```javascript\nuseHeadSafe({\n  meta: [{\n    name: \u0027description\u0027,\n    content: \u0027legitimate content\u0027,\n    \u0027data-x onclick=alert(document.domain) y\u0027: \u0027z\u0027\n  }]\n})\n```\n\n### Realistic scenario\n\nA Nuxt app accepts SEO metadata from a CMS or user profile. The developer uses `useHeadSafe()` as the docs recommend. An attacker puts a `data-*` key with spaces and an event handler into their input. The payload renders into the HTML on every page load.\n\n## Suggested fix\n\nFor vulnerability 1, validate that attribute names only contain characters legal in HTML attributes:\n\n```typescript\nconst SAFE_ATTR_RE = /^[a-zA-Z][a-zA-Z0-9\\-]*$/\n\nfunction acceptDataAttrs(value: Record\u003cstring, string\u003e) {\n  return Object.fromEntries(\n    Object.entries(value || {}).filter(\n      ([key]) =\u003e (key === \u0027id\u0027 || key.startsWith(\u0027data-\u0027)) \u0026\u0026 SAFE_ATTR_RE.test(key)\n    ),\n  )\n}\n```",
  "id": "GHSA-g5xx-pwrp-g3fv",
  "modified": "2026-03-12T19:14:22Z",
  "published": "2026-03-12T14:19:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31860"
    },
    {
      "type": "WEB",
      "url": "https://github.com/unjs/unhead/commit/9ecc4f9568b0e23938f36d4b23fcfa4a18a89045"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/unjs/unhead"
    },
    {
      "type": "WEB",
      "url": "https://github.com/unjs/unhead/releases/tag/v2.1.11"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Unhead has XSS bypass in `useHeadSafe` via attribute name injection and case-sensitive protocol check"
}

FKIE_CVE-2026-31860

Vulnerability from fkie_nvd - Published: 2026-03-12 18:16 - Updated: 2026-03-16 17:56

Severity ?

6.1 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv	Exploit, Mitigation, Vendor Advisory
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv	Exploit, Mitigation, Vendor Advisory

Impacted products

	Vendor	Product	Version
	unjs	unhead	*

JSON

To clipboard

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:unjs:unhead:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "67F3AFEA-7DE2-46CC-AC50-D8B49F57C37E",
              "versionEndExcluding": "2.1.11",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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 \u003chead\u003e 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."
    },
    {
      "lang": "es",
      "value": "Unhead es un gestor de cabecera de documento y plantillas. Antes de la 2.1.11, se puede eludir useHeadSafe() para inyectar atributos HTML arbitrarios, incluyendo manejadores de eventos, en etiquetas  renderizadas por SSR. Este es el composable que la documentaci\u00f3n de Nuxt recomienda para manejar de forma segura contenido generado por el usuario. La funci\u00f3n acceptDataAttrs (safe.ts, l\u00ednea 16-20) permite cualquier clave de propiedad que comience con \u0027data-\u0027 hasta el HTML final. Solo verifica el prefijo, no si la clave contiene espacios u otros caracteres que rompen el an\u00e1lisis de atributos HTML. Esta vulnerabilidad est\u00e1 corregida en la 2.1.11."
    }
  ],
  "id": "CVE-2026-31860",
  "lastModified": "2026-03-16T17:56:34.140",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.1,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "LOW",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 2.7,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "userInteraction": "PASSIVE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-03-12T18:16:24.227",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "tags": [
        "Exploit",
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/unjs/unhead/security/advisories/GHSA-g5xx-pwrp-g3fv"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-79"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

CVE-2026-31860 (GCVE-0-2026-31860)

GHSA-G5XX-PWRP-G3FV

Summary

Details

PoC

Realistic scenario

Suggested fix

FKIE_CVE-2026-31860

Tags

Sightings

Nomenclature