CVE-2026-50290: @asymmetric-effort/specifyjs · CSS expression sanitization is bypassable in renderToString
Affects @asymmetric-effort/specifyjsSource GCVE Database
Not known to be exploited · CVSS 5.3 Medium : upgrade to 0.2.136 when convenient.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.2.136
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 21 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade @asymmetric-effort/specifyjs to 0.2.136.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| npm@asymmetric-effort/specifyjs | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
## 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.