CVE-2026-50290

Medium

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.

SeverityMedium

CVSS5.3

Exploit probability—

Product@asymmetric-effort/specifyjs

PublishedAug 21, 2026

First seenAug 21, 2026

Weakness typeCWE-79Cross-site scripting (XSS)

How to fix

Update

@asymmetric-effort/specifyjs0.2.136 or later

Affected products

Product	Affected versions	Fixed in
@asymmetric-effort/specifyjsnpm	v < 0.2.136	0.2.136

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