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VulnerabilityPublished

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

Affects @asymmetric-effort/specifyjsSource GCVE Database

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Authoritative record:CVE-2026-50290· Medium 5.3

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

CVSS 4.0 base score
5.3Medium
How severe the flaw is on the 0–10 CVSS scale.
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:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 21 Aug 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
npm@asymmetric-effort/specifyjsAffected
  • <0.2.136
Fixed in
  • 0.2.136

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.

References

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