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CVE-2026-33889— ApostropheCMS: Stored XSS via CSS Custom Property Injection in `@apostrophecms/color-field` Escaping Style Tag Context

CVSS 5.4 · Medium EPSS 0.03% · P11
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I. Basic Information for CVE-2026-33889

Vulnerability Information
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Vulnerability Title
ApostropheCMS: Stored XSS via CSS Custom Property Injection in `@apostrophecms/color-field` Escaping Style Tag Context
Source: NVD (National Vulnerability Database)
Vulnerability Description
ApostropheCMS is an open-source Node.js content management system. Versions 4.28.0 and prior contain a stored cross-site scripting vulnerability in the @apostrophecms/color-field module, where color values prefixed with -- bypass TinyColor validation intended for CSS custom properties, and the launder.string() call performs only type coercion without stripping HTML metacharacters. These unsanitized values are then concatenated directly into <style> tags both in per-widget style elements rendered for all visitors and in the global stylesheet rendered for editors, with the output marked as safe HTML. An editor can inject a value which closes the style tag and executes arbitrary JavaScript in the browser of every visitor to any page containing the affected widget. This enables mass session hijacking, cookie theft, and privilege escalation to administrative control if an admin views draft content. This issue has been fixed in version 4.29.0.
Source: NVD (National Vulnerability Database)
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Source: NVD (National Vulnerability Database)
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: NVD (National Vulnerability Database)
Vulnerability Title
ApostropheCMS 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
ApostropheCMS是Apostrophe Technologies开源的一个全栈内容管理系统。 ApostropheCMS 4.28.0及之前版本存在安全漏洞，该漏洞源于@apostrophecms/color-field模块存在存储型跨站脚本漏洞，可能导致任意JavaScript执行。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
apostrophecmsapostrophe < 4.29.0 -

II. Public POCs for CVE-2026-33889

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III. Intelligence Information for CVE-2026-33889

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Same Patch Batch · apostrophecms · 2026-04-15 · 6 CVEs total

CVE-2026-355698.7 HIGHApostropheCMS: Stored XSS in SEO Fields Leads to Authenticated API Data Exposure in Apostr
CVE-2026-401866.1 MEDIUMApostropheCMS: sanitize-html allowedTags Bypass via Entity-Decoded Text in nonTextTags Ele
CVE-2026-398575.3 MEDIUMInformation Disclosure via `choices`/`counts` Query Parameters Bypassing publicApiProjecti
CVE-2026-338885.3 MEDIUMApostropheCMS: publicApiProjection Bypass via `project` Query Builder in Piece-Type REST A
CVE-2026-338773.7 LOWApostropheCMS: User Enumeration via Timing Side Channel in Password Reset Endpoint

IV. Related Vulnerabilities

Same product: apostrophe
Same vendor: apostrophecms
Same weakness: CWE-79

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