CVE-2026-63406 — anycable

Summary

The telemetry subsystem embeds a hardcoded auth token ("secret") in the public source and transmits raw CLI arguments—including --secret, --jwt_secret, and --http_rpc_secret values—to a third-party telemetry endpoint.

Details

In telemetry/config.go line 12, var authToken = "secret" is committed in the public repository and used to authenticate to https://telemetry.anycable.io. In telemetry/telemetry.go, clusterFingerprint() (line 320) calls both anycableFileConfig(c.ConfigFilePath) (line 333), which reads the full TOML config file contents, and anycableCLIArgs() (line 402), which reads os.Args[1:] verbatim—including any --secret=..., --jwt_secret=..., --http_rpc_secret=... arguments. Both raw values are passed to generateDigest() (line 373), meaning the actual secret strings flow through the code path and are included in telemetry data sent to the third-party server. Since the hardcoded authToken = "secret" is public, any attacker who can perform DNS hijacking or is positioned on the network path can intercept and read the telemetry payload containing operator credentials.

PoC

1. Read telemetry/config.go in the public repo to find authToken = "secret".
2. Set up a DNS spoof for telemetry.anycable.io pointing to an attacker-controlled server.
3. Start anycable-go with --secret=my-production-secret.
4. The server sends a POST to the attacker's endpoint with the telemetry JSON payload. The clusterFingerprint field contains data derived from raw os.Args including --secret=my-production-secret.

Impact

In MITM/DNS-hijack scenarios, production secrets (JWT secrets, broadcast keys, RPC auth) are exposed to third parties. The hardcoded authToken = "secret" provides no protection since it is known to anyone reading the open-source code.

Fix

1. Remove the hardcoded authToken from source; generate or require operator configuration at build time or deployment time. 2. Remove anycableCLIArgs() from the fingerprint computation, or sanitize it to exclude values of secret-bearing flags before hashing. 3. Add a documented opt-out mechanism for telemetry.