CVE-2026-50290: @asymmetric-effort/specifyjs: CSS expression sanitization is bypassable in renderToString

July 2, 2026

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.

References

github.com/advisories/GHSA-93q6-wwjh-jc6h
github.com/asymmetric-effort/specifyjs/commit/25d1fb491d99479efdf501f5f75e0bb80c908f0a
github.com/asymmetric-effort/specifyjs/security/advisories/GHSA-93q6-wwjh-jc6h
nvd.nist.gov/vuln/detail/CVE-2026-50290

Code Behaviors & Features

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