---
id: CVE-2026-50290
title: >-
  @asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in
  renderToString
summary: >-
  @asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in
  renderToString
severity: medium
cwe:
  - CWE-79
vendor: asymmetric-effort
product: '@asymmetric-effort/specifyjs'
ecosystem: npm
affected:
  - '@asymmetric-effort/specifyjs < 0.2.136'
patched:
  - '@asymmetric-effort/specifyjs 0.2.136'
published: '2026-07-02'
updated: '2026-07-02'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-93q6-wwjh-jc6h'
references:
  - url: >-
      https://github.com/asymmetric-effort/specifyjs/security/advisories/GHSA-93q6-wwjh-jc6h
  - url: >-
      https://github.com/asymmetric-effort/specifyjs/commit/25d1fb491d99479efdf501f5f75e0bb80c908f0a
  - url: 'https://github.com/advisories/GHSA-93q6-wwjh-jc6h'
tags:
  - ghsa
  - npm
ingestedAt: '2026-07-02T19:41:50.952Z'
epss: 0.00489
epssPercentile: 0.39534
---

## Overview

## Finding

**Location**: `core/src/server/render-to-string.ts:307-311`

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(`).

**Mitigating Factor**: These CSS injection vectors only work in legacy browsers (IE6-IE10). SpecifyJS targets modern browsers.

## Status

**Fixed in v0.2.136** — CSS sanitization now normalizes unicode escapes and strips CSS comments before pattern matching. Also checks for `behavior:`, `-moz-binding`, and `-o-link` patterns.

## Affected packages

- `@asymmetric-effort/specifyjs < 0.2.136`

## Remediation

Upgrade to a patched release:

- `@asymmetric-effort/specifyjs 0.2.136`