CVE-2026-126209

5.3 MEDIUM 0.4% exploit odds Fix listed XSS Web app

What it is

Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. From 2.25.0 until 2.25.3, Loofah::HTML5::Scrub.allowed_uri? strips whitespace and control characters before decoding a semicolon-less numeric character reference, changing where the reference ends and hiding a javascript: or vbscript: scheme that a browser reconstructs. The bypass applies to encoded colons and encoded scheme letters when a stripped character terminates the numeric reference. An application that renders the approved value in href or another browser-interpreted URI attribute can allow cross-site scripting, and Rails::HTML::Sanitizer.allowed_uri? re-exports the affected helper. Loofah's default sanitize() path is not affected because Nokogiri decodes entities before URI evaluation. This issue is fixed in version 2.25.3.

At a glance

Exploitability: Can be exploited over the network without logging in, but needs a user to act. Limited direct impact.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-11-10 20:07 UTC ReservedThe CVE id was reserved by its CNA
2026-11-12 21:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-11-12 22:09 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 5.3 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-11-12 21:17 UTC
Last modified: 2026-11-12 22:09 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-79 · Cross-site scripting
Record status: Awaiting Analysis

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-2026-126209.md and follow it. Check whether this project is affected by CVE-2026-126209. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

· More options · Status badge

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record