CVE-2026-50290

@asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString

Published Aug 21, 2026 CVSS 4.0 · 5.3 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-93q6-wwjh-jc6h @asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString
History
Type Values Removed Values Added
First Time appeared Asymmetric-effort
Asymmetric-effort specifyjs
Vendors & Products Asymmetric-effort
Asymmetric-effort specifyjs
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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.
Title @asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString
Weaknesses CWE-79
References
Metrics cvssV4_0

{'score': 5.3, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 21, 2026, 8:07 PM
Reserved
Jun 4, 2026, 4:26 PM
Status
Deferred
Published
Aug 21, 2026, 8:16 PM
Modified
Oct 14, 2026, 7:10 PM