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Vulnerability details: VCID-4ea6-rues-sygu
Vulnerability ID VCID-4ea6-rues-sygu
Aliases CVE-2026-31873
GHSA-5339-hvwr-7582
Summary Unhead is a document head and template manager. Prior to 2.1.11, The link.href check in makeTagSafe (safe.ts) uses String.includes(), which is case-sensitive. Browsers treat URI schemes case-insensitively. DATA:text/css,... is the same as data:text/css,... to the browser, but 'DATA:...'.includes('data:') returns false. An attacker can inject arbitrary CSS for UI redressing or data exfiltration via CSS attribute selectors with background-image callbacks. This vulnerability is fixed in 2.1.11.
Status Published
Exploitability None
Weighted Severity None
Risk None
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
epss 0.0002 https://api.first.org/data/v1/epss?cve=CVE-2026-31873
cvssv3.1_qr LOW https://github.com/advisories/GHSA-5339-hvwr-7582
cvssv3.1 0.0 https://github.com/unjs/unhead
generic_textual LOW https://github.com/unjs/unhead
cvssv3.1 0.0 https://github.com/unjs/unhead/releases/tag/v2.1.11
generic_textual LOW https://github.com/unjs/unhead/releases/tag/v2.1.11
cvssv3.1 0 https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
cvssv3.1 0.0 https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
cvssv3.1_qr LOW https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
generic_textual LOW https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
ssvc Track https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
cvssv3.1 0.0 https://nvd.nist.gov/vuln/detail/CVE-2026-31873
generic_textual LOW https://nvd.nist.gov/vuln/detail/CVE-2026-31873
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2026-31873
https://github.com/unjs/unhead
https://github.com/unjs/unhead/releases/tag/v2.1.11
https://nvd.nist.gov/vuln/detail/CVE-2026-31873
GHSA-5339-hvwr-7582 https://github.com/advisories/GHSA-5339-hvwr-7582
GHSA-5339-hvwr-7582 https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N Found at https://github.com/unjs/unhead
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N Found at https://github.com/unjs/unhead/releases/tag/v2.1.11
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N Found at https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

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Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N Found at https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

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high

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Vector: SSVCv2/E:P/A:Y/T:P/P:M/B:A/M:M/D:T/2026-03-12T17:46:23Z/ Found at https://github.com/unjs/unhead/security/advisories/GHSA-5339-hvwr-7582
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-31873
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

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none

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Exploit Prediction Scoring System (EPSS)
Percentile 0.05725
EPSS Score 0.0002
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T16:44:46.782160+00:00 Vulnrichment Import https://github.com/cisagov/vulnrichment/blob/develop/2026/31xxx/CVE-2026-31873.json 38.6.0