flavorjones Loofah 2.25.2 Scrub Scrub.allowed_uri cross site scripting

Summaryinfo

A vulnerability was found in flavorjones Loofah 2.25.2. It has been classified as problematic. This issue affects the function Loofah::HTML5::Scrub.allowed_uri of the component Scrub. Performing a manipulation results in cross site scripting. This vulnerability is cataloged as CVE-2026-126206. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, was found in flavorjones Loofah 2.25.2. This affects the function Loofah::HTML5::Scrub.allowed_uri of the component Scrub. The manipulation with an unknown input leads to a cross site scripting vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. The summary by CVE is:

Loofah is a general library for manipulating and transforming HTML/XML documents and fragments, built on top of Nokogiri. In 2.25.2, Loofah::HTML5::Scrub.allowed_uri? treats a data URI mediatype containing the HTML5 named solidus reference / as malformed and falls back to the allowed text/plain, while a browser decodes the reference and interprets the same value as text/html. An application that validates a user-controlled URL with this helper and renders the approved value in href or another browser-interpreted URI attribute can allow cross-site scripting. Rails::HTML::Sanitizer.allowed_uri? re-exports the affected helper. Loofah's default sanitize() path is not affected because Nokogiri decodes the entity before URI validation. This issue is fixed in version 2.25.3.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-126206 since 11/10/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 2.25.3 eliminates this vulnerability.

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Productinfo

Vendor

• flavorjones

Name

• Loofah

Version

• 2.25.2

Website

• Product: https://github.com/flavorjones/loofah/

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