rails rails-html-sanitizer up to 1.7.1 PermitScrubber cross site scripting

Summaryinfo

A vulnerability, which was classified as problematic, has been found in rails rails-html-sanitizer up to 1.7.1. The impacted element is an unknown function of the component PermitScrubber. Performing a manipulation results in cross site scripting. This vulnerability is known as CVE-2026-128069. Remote exploitation of the attack is possible. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in rails rails-html-sanitizer up to 1.7.1. It has been classified as problematic. This affects an unknown functionality of the component PermitScrubber. 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:

rails-html-sanitizer is responsible for sanitizing HTML fragments in Rails applications. Before 1.7.2, the HTML4 and HTML5 variants of Rails::HTML::SafeListSanitizer reuse one Rails::HTML::PermitScrubber across calls and mutate its tags and attributes without synchronization. In a multithreaded process, concurrent sanitize calls using different tags: or attributes: options can interleave and cause one call to use the other call's allowlist. If a permissive call admits a script element or event-handler attribute, output expected to be sanitized under a stricter policy can retain it and cause cross-site scripting when rendered. Applications that are single-threaded, use one identical allowlist everywhere, or provide a separate scrubber: are not affected. This issue is fixed in version 1.7.2.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-128069 since 11/12/2026. 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. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 1.7.2 eliminates this vulnerability.

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Productinfo

Vendor

• rails

Name

• rails-html-sanitizer

Version

• 1.7.0
• 1.7.1

Website

• Product: https://github.com/rails/rails-html-sanitizer/

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