Executive brief
Ech0 is a peer connection management tool used to establish secure connections between services. A server-side request forgery vulnerability in the fetchPeerConnectInfo function allows authenticated attackers to force the server to make HTTP requests to arbitrary URLs, including internal services and cloud metadata endpoints. An attacker can exploit this to extract sensitive credentials and metadata, potentially leading to lateral movement within cloud environments or internal networks.
Technical details
The vulnerability exists in the fetchPeerConnectInfo function (internal/service/connect/connect.go, lines 214-239) which uses httpUtil.SendRequest to fetch peer connection data without URL validation. The codebase contains a secure alternative, httpUtil.SendSafeRequest, which implements ValidatePublicHTTPURL and blocks private IP ranges, but fetchPeerConnectInfo fails to use it. Authenticated users can supply malicious connect_url parameters pointing to internal services (e.g., 169.254.169.254 for AWS metadata, kubernetes.default.svc.cluster.local for Kubernetes API) and trigger SSRF via health check endpoints or peer connection operations. The vulnerability requires authentication but has no user interaction requirement and can access highly sensitive infrastructure metadata. The fix is available in version 4.7.3.
Affected products
- lin-snow Ech0 before 4.7.3
Timeline
- 2026-05-03: disclosed: GitHub security advisory published
- 2026: patched: Patched in version 4.7.3
- 2026-08-25: advisory: CVE-2026-79659 published