CVE-2026-50290: asymmetric-effort specifyjs · Cross-site Scripting
Affects asymmetric-effort specifyjsSource CVE Database V5
Not known to be exploited · CVSS 5.3 Medium : upgrade to 0.2.136 when convenient.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 41% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-08-21.
- 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
Weaponised: 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 26 Oct 2026.
What to do
Upgrade asymmetric-effort specifyjs to 0.2.136.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| asymmetric-effortspecifyjs | Affected
| Fixed in
|
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.