CVE-2026-50290

5.3 MEDIUM 0.5% exploit odds Fix listed XSS

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.
Exploit odds: 0.5% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-08-21 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-14 19:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.5% in the next 30 days (EPSS).
Severity: 5.3 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-08-21 20:16 UTC
Last modified: 2026-10-14 19:10 UTC
Exploit probability: 0.5% · EPSS, next 30 days
Weakness: CWE-79 · Cross-site scripting
Record status: Deferred

Attack profile CVSS 4.0 · 5.3

Attack vector: Network
Complexity: Low
Attack requirements: None
Privileges needed: None
User interaction: Passive
Confidentiality: None
Integrity: None
Availability: None

Raw 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-50290.md and follow it. Check whether this project is affected by CVE-2026-50290. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record