If a JWT secret key leaks to an unintended audience, it can have serious
security implications for the corresponding application. The secret key is used
to encode and decode JWTs when using a symmetric signing algorithm, and an
attacker could potentially use it to perform malicious actions.

For example, an attacker could use the secret key to create their own
authentication tokens that appear to be legitimate, allowing them to bypass
authentication and gain access to sensitive data or functionality.

In the worst-case scenario, an attacker could be able to execute arbitrary code
on the application by abusing administrative features, and take over its hosting
server.