CVE-2026-39315 | unjs unhead up to 2.1.12 safe.ts useHeadSafe incomplete blacklist (GHSA-95h2-gj7x-gx9w)

VDB-356647 · CVE-2026-39315 · GHSA-95H2-GJ7X-GX9W UNJS UNHEAD UP TO 2.1.12 SAFE.TS USEHEADSAFE INCOMPLETE BLACKLIST HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.0 $0-$5k 0.58+ Summaryinfo A vulnerability marked as critical has been reported in unjs unhead up to 2.1.12. Impacted is the function useHeadSafe of the file packages/unhead/src/plugins/safe.ts. This manipulation causes incomplete blacklist. This vulnerability is tracked as CVE-2026-39315. The attack is possible to be carried out remotely. No exploit exists. It is suggested to upgrade the affected component. Detailsinfo A vulnerability has been found in unjs unhead up to 2.1.12 and classified as critical. Affected by this vulnerability is the function useHeadSafe of the file packages/unhead/src/plugins/safe.ts. The manipulation with an unknown input leads to a incomplete blacklist vulnerability. The CWE definition for the vulnerability is CWE-184. The product implements a protection mechanism that relies on a list of inputs (or properties of inputs) that are not allowed by policy or otherwise require other action to neutralize before additional processing takes place, but the list is incomplete, leading to resultant weaknesses. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is: Unhead is a document head and template manager. Prior to 2.1.13, useHeadSafe() is the composable that Nuxt's own documentation explicitly recommends for rendering user-supplied content in safely. Internally, the hasDangerousProtocol() function in packages/unhead/src/plugins/safe.ts decodes HTML entities before checking for blocked URI schemes (javascript:, data:, vbscript:). The decoder uses two regular expressions with fixed-width digit caps. The HTML5 specification imposes no limit on leading zeros in numeric character references. When a padded entity exceeds the regex digit cap, the decoder silently skips it. The undecoded string is then passed to startsWith('javascript:'), which does not match. makeTagSafe() writes the raw value directly into SSR HTML output. The browser's HTML parser decodes the padded entity natively and constructs the blocked URI. This vulnerability is fixed in 2.1.13. It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-39315 since 04/06/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1562.006 according to MITRE ATT&CK. Upgrading to version 2.1.13 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 961ea781e091853812ffe17f8cda17105d2d2299 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version. Productinfo Vendor unjs Name unhead Version 2.1.0 2.1.1 2.1.2 2.1.3 2.1.4 2.1.5 2.1.6 2.1.7 2.1.8 2.1.9 2.1.10 2.1.11 2.1.12 License open-source Website Product: https://github.com/unjs/unhead/ CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 6.2 VulDB Meta Temp Score: 6.0 VulDB Base Score: 6.3 VulDB Temp Score: 6.0 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 6.1 CNA Vector (GitHub_M): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Incomplete blacklist CWE: CWE-184 / CWE-183 / CWE-20 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: unhead 2.1.13 Patch: 961ea781e091853812ffe17f8cda17105d2d2299 Timelineinfo 04/06/2026 CVE reserved 04/09/2026 +3 days Advisory disclosed 04/09/2026 +0 days VulDB entry created 04/09/2026 +0 days VulDB entry last update Sourcesinfo Product: github.com Advisory: GHSA-95h2-gj7x-gx9w Status: Confirmed CVE: CVE-2026-39315 (🔒) GCVE (CVE): GCVE-0-2026-39315 GCVE (VulDB): GCVE-100-356647 Entryinfo Created: 04/09/2026 21:35 Changes: 04/09/2026 21:35 (69) Complete: 🔍 Cache ID: 99:68B:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸