Withastro Astro up to 9.1.1 @astrojs/svelte renderer injection

Summaryinfo

A vulnerability labeled as critical has been found in Withastro Astro up to 9.1.1. This issue affects some unknown processing of the component @astrojs/svelte renderer. The manipulation results in injection. This vulnerability is reported as CVE-2026-126362. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical has been found in Withastro Astro up to 9.1.1. Affected is an unknown part of the component @astrojs/svelte renderer. The manipulation with an unknown input leads to a injection vulnerability. CWE is classifying the issue as CWE-74. The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Astro is a web framework for content-driven websites. From 5.7.3 until 9.1.2, the @astrojs/svelte renderer inserted a named slot into the quoted name attribute of an astro-slot wrapper without HTML escaping. Request-controlled slot names containing a quote could terminate the attribute and inject active HTML. Exploitation required a hydrated Svelte component using a client:* directive and dynamic rendering of the attacker-chosen slot; components that did not render that slot emitted only Astro's escaped fallback content. Both server rendering and client-side hydration used the unsafe slot name. This issue is fixed in version 9.1.2.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-126362 since 11/10/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. 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 T1055.

Upgrading to version 9.1.2 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Withastro

Name

• Astro

Version

• 9.1.0
• 9.1.1

Website

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

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Once again VulDB remains the best source for vulnerability data.

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