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CVE-2026-50290— @asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString

Quick assessment

Affected
asymmetric-effort specifyjs
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

SpecifyJS 是一个声明式的 TypeScript 用户界面框架。在 0.2.136 版本之前，CSS 值 sanitization（ sanitization 指对输入进行净化、过滤以确保安全）仅通过简单的正则表达式过滤 和 ，但攻击者可以通过 CSS Unicode 转义序列（如 ）、空字节（null bytes）或 CSS 注释（如 ）绕过该机制。这些 CSS 注入向量仅在旧版浏览器（IE6-IE10）中有效，而 SpecifyJS 面向的是现代浏览器。 从版本 0.2.136 开始，CSS sanit

CVSS 5.3 · Medium EPSS 0.36% · P29

Possible ATT&CK Techniques 1 AI

T1189 · Drive-by Compromise

Affected Version Matrix 1

VendorProduct Version RangeStatus
asymmetric-effort specifyjs < 0.2.136 affected
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I. Basic Information for CVE-2026-50290

Vulnerability Information
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Vulnerability Title
@asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString
Source: CVE Program / CVE List V5
Vulnerability Description
SpecifyJS is a declarative TypeScript user interface framework. Prior to version 0.2.136, CSS value sanitization stripped `expression(` and `url(javascript:` using simple regex, but could be bypassed with CSS unicode escapes (`\65xpression(`), null bytes, or CSS comments (`exp/**/ression(`). These CSS injection vectors only work in legacy browsers (IE6-IE10). SpecifyJS targets modern browsers. Starting in version 0.2.136, CSS sanitization now normalizes unicode escapes and strips CSS comments before pattern matching. Also checks for `behavior:`, `-moz-binding`, and `-o-link` patterns.
Source: CVE Program / CVE List V5
CVSS Information
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
Source: CVE Program / CVE List V5
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: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
asymmetric-effort specifyjs < 0.2.136 -

II. Public POCs for CVE-2026-50290

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III. Intelligence Information for CVE-2026-50290

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Patches & Fixes for CVE-2026-50290 (1)

Vendor Advisories for CVE-2026-50290 (1)

IV. Related Vulnerabilities

Same product: specifyjs
Same vendor: asymmetric-effort
Same weakness: CWE-79

V. Comments for CVE-2026-50290

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