CVE-2026-35036: Ech0 Affected by Unauthenticated Server-Side Request Forgery in Website Preview Feature

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-06 · updated 2026-10-24
Weakness: CWE-918

Description

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.

Affected products

lin-snow Ech0: before 4.2.8 — fixed in 4.2.8

How to fix

Upgrade to a fixed version: lin-snow Ech0 4.2.8. Check the vendor advisory for mitigations.

References

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