lin-snow Ech0 up to 4.2.7 Response Body /api/website/title server-side request forgery

Summaryinfo

A vulnerability classified as critical has been found in lin-snow Ech0 up to 4.2.7. Impacted is an unknown function of the file /api/website/title of the component Response Body Handler. The manipulation leads to server-side request forgery. This vulnerability is listed as CVE-2026-35036. The attack may be initiated remotely. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in lin-snow Ech0 up to 4.2.7 and classified as critical. This issue affects some unknown processing of the file /api/website/title of the component Response Body Handler. The manipulation with an unknown input leads to a server-side request forgery vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Ech0 is an open-source, self-hosted publishing platform for personal idea sharing. Prior to 4.2.8, Ech0 implements link preview (editor fetches a page title) through GET /api/website/title. That is legitimate product behavior, but the implementation is unsafe: the route is unauthenticated, accepts a fully attacker-controlled URL, performs a server-side GET, reads the entire response body into memory (io.ReadAll). There is no host allowlist, no SSRF filter, and InsecureSkipVerify: true on the outbound client. Anyone who can reach the instance can force the Ech0 server to open HTTP/HTTPS URLs of their choice as seen from the server’s network position (Docker bridge, VPC, localhost from the process view). This vulnerability is fixed in 4.2.8.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-35036 since 03/31/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

Upgrading to version 4.2.8 eliminates this vulnerability.

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Productinfo

Vendor

• lin-snow

Name

• Ech0

Version

• 4.2.0
• 4.2.1
• 4.2.2
• 4.2.3
• 4.2.4
• 4.2.5
• 4.2.6
• 4.2.7

Website

• Product: https://github.com/lin-snow/Ech0/

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