Withastro Astro up to 7.3.1 JSX/MDX Renderer cross site scripting

Summaryinfo

A vulnerability classified as problematic was found in Withastro Astro up to 7.3.1. This impacts an unknown function of the component JSX/MDX Renderer. Such manipulation leads to cross site scripting. This vulnerability is listed as CVE-2026-114128. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Withastro Astro up to 7.3.1. Affected by this issue is an unknown function of the component JSX/MDX Renderer. 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. CVE summarizes:

Astro is a web framework for content-driven websites. Prior to 7.3.2, Astro's JSX and MDX rendering pipeline treats string children of script and style elements as trusted HTML without distinguishing compiler-generated literal content from dynamic expression values. An application that passes attacker-controlled data directly as a dynamic child can allow a value containing a closing script or style tag to terminate the element and inject arbitrary HTML and JavaScript. Other JSX expression contexts escape dynamic strings automatically; the issue is limited to script and style children rendered through the astro:jsx renderer, including MDX components. Successful exploitation can produce reflected or stored cross-site scripting under the application's origin. This issue is fixed in 7.3.2.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-114128 since 10/20/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1059.007.

Upgrading to version 7.3.2 eliminates this vulnerability.

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Productinfo

Vendor

• Withastro

Name

• Astro

Version

• 7.3.0
• 7.3.1

Website

• Product: https://github.com/withastro/astro/

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