withastro up to 9.5.3 server-side request forgery

Summaryinfo

A vulnerability categorized as critical has been discovered in withastro astro up to 9.5.3. Affected by this issue is some unknown functionality. The manipulation results in server-side request forgery. This vulnerability is reported as CVE-2026-25545. The attack can be launched remotely. No exploit exists. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, was found in withastro astro up to 9.5.3. Affected is an unknown functionality. The manipulation with an unknown input leads to a server-side request forgery vulnerability. CWE is classifying the issue as CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Astro is a web framework. Prior to version 9.5.4, Server-Side Rendered pages that return an error with a prerendered custom error page (eg. `404.astro` or `500.astro`) are vulnerable to SSRF. If the `Host:` header is changed to an attacker's server, it will be fetched on `/500.html` and they can redirect this to any internal URL to read the response body through the first request. An attacker who can access the application without `Host:` header validation (eg. through finding the origin IP behind a proxy, or just by default) can fetch their own server to redirect to any internal IP. With this they can fetch cloud metadata IPs and interact with services in the internal network or localhost. For this to be vulnerable, a common feature needs to be used, with direct access to the server (no proxies). Version 9.5.4 fixes the issue.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-25545 since 02/02/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The technical details are unknown and an exploit is not available.

Upgrading to version 9.5.4 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch e01e98b063e90d274c42130ec2a60cc0966622c9 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• withastro

Name

• astro

Version

• 9.5.0
• 9.5.1
• 9.5.2
• 9.5.3

License

• open-source

Website

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

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