api: Shared OAuth Signing Key Between Different Instances

api is a module for FreePBX@, which is an open source GUI that controls and manages Asterisk© (PBX). In versions lower than 15.0.13, 16.0.2 through 16.0.14, 17.0.1 and 17.0.2, there is an identical OAuth private key used across multiple systems that installed the same FreePBX RPM or DEB package. An attacker with access to the shared OAuth private key could forge JWT tokens, bypass authentication, and potentially gain full access to both REST and GraphQL APIs. Systems with the "api" module enabled, configured and previously activated by an administrator for remote inbound connections may be affected. This issue is fixed in versions 15.0.13, 16.0.15 and 17.0.3.