Vulnerability · Published Aug 21, 2026 · Assigned by GitHub_M
CVE-2026-50290@asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString
Medium 5.3
In plain English
A medium-severity cross-site scripting in specifyjs from asymmetric-effort. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @asymmetric-effort/specifyjs | 0.2.136 | GHSA-93q6-wwjh-jc6h |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| asymmetric-effort | specifyjs | < 0.2.136 |
Weakness: CWE-79 · 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