lud oaskit 0.1.0/0.14.0 Error default.ex cross site scripting

Summaryinfo

A vulnerability marked as problematic has been reported in lud oaskit 0.1.0/0.14.0. The affected element is the function Oaskit.ErrorHandler.Default.format_reason/Oaskit.ErrorHandler.Default.reason_to_html of the file lib/oaskit/error_handler/default.ex of the component Error Handler. The manipulation leads to cross site scripting. This vulnerability is referenced as CVE-2026-66296. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in lud oaskit 0.1.0/0.14.0 and classified as problematic. This issue affects the function Oaskit.ErrorHandler.Default.format_reason/Oaskit.ErrorHandler.Default.reason_to_html of the file lib/oaskit/error_handler/default.ex of the component Error Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to 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. Impacted is integrity. The summary by CVE is:

Improper Neutralization of Input During Web Page Generation (XSS) vulnerability in lud oaskit allows reflected cross-site scripting via the default HTML error handler. Oaskit.ErrorHandler.Default.format_reason/4 and Oaskit.ErrorHandler.Default.reason_to_html/1 in lib/oaskit/error_handler/default.ex render request-validation failures as an HTML page whenever the request's Accept header contains html, interpolating request-controlled strings into that page without HTML escaping. The unescaped values are object keys taken from a request body or from an object or deepObject query parameter, which appear in the JSON Schema error's instance path when a schema rejects them (for example under additionalProperties: false), and the raw Content-Type header, reflected in unsupported-media-type errors when it fails to parse. Because browsers send Accept: text/html on ordinary top-level navigation, a crafted GET link is sufficient to trigger the error page; no form submission, custom Content-Type, or attacker-controlled script on the victim's side is required. A payload such as filter[</code></h2><script>alert(document.domain)</script>]=x terminates the enclosing markup and the injected script executes in the origin of the application using oaskit, giving it access to that origin's cookies, session, and same-origin responses. Both HTML error rendering and the vulnerable handler are enabled by default: Oaskit.Plugs.ValidateRequest defaults :html_errors to true and :error_handler to Oaskit.ErrorHandler.Default, so applications following the documented usage are affected without any opt-in. This issue affects oaskit: from 0.1.0 before 0.14.1.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-66296 since 07/24/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful 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 0.14.1 eliminates this vulnerability.

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Productinfo

Vendor

• lud

Name

• oaskit

Version

• 0.1.0
• 0.14.0

Website

• Product: https://github.com/lud/oaskit/

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