GHSA-wc4h-2348-jc3p

Summary

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.

Attacker outcome : 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). Go’s default http.Client follows redirects (unless disabled). Redirect chains can move the server-side request from an allowed-looking host to an internal target; the code does not disable this in SendRequest.

Affected Components

Ech0 codebase:

• internal/handler/common/common.go
  Handles the /api/website/title endpoint and accepts user-controlled URL input.

• internal/service/common/common.go
  Processes the request and invokes the outbound HTTP fetch (GetWebsiteTitle).

• internal/util/http/http.go
  Performs the HTTP request (SendRequest) with the following insecure configurations:

  • No URL validation or allowlist
  • Redirects enabled (default client behavior)
  • InsecureSkipVerify: true

PoC

Environment: Ech0 listening on http://127.0.0.1:6277 (e.g. Docker image sn0wl1n/ech0:latest). No cookies or Authorization header.

Step 1 — baseline: unauthenticated server-side fetch (public URL):

curl.exe -sS -m 20 "http://127.0.0.1:6277/api/website/title?website_url=https://example.com"

Observed result (verified): HTTP 200, JSON with code: 1 and data Example Domain — proves the Ech0 process performed an outbound GET without any client auth.

**Step 2 — impact: host-bound page...