@asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString (CVE-2026-50290) | HOL Guard CVE

Medium · CVSS 5.3CVE-2026-50290GHSA-93Q6-WWJH-JC6H

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

Answer in brief

CVE-2026-50290 records a Medium severity (CVSS 5.3) vulnerability in @asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString. The current sources do not mark it as known exploited. The current feed maps asymmetric-effort/specifyjs (generic), @asymmetric-effort/specifyjs (npm). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 21, 2026Updated Aug 21, 2026Source checked Sep 17, 2026First seen by HOL Jul 2, 2026Material review Aug 21, 2026

Upstream Advisory

Key facts

Risk: Medium · CVSS 5.3
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 5.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps asymmetric-effort/specifyjs (generic), @asymmetric-effort/specifyjs (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
asymmetric-effort/specifyjsgeneric	< 0.2.136	Not reported
@asymmetric-effort/specifyjsnpm	<0.2.136	0.2.136

Recommended response

Check inventory. Check lockfiles and deployed manifests for asymmetric-effort/specifyjs, @asymmetric-effort/specifyjs.
Review the reported fix. Update @asymmetric-effort/specifyjs to 0.2.136 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 21, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 21, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Jul 2, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.