next-auth before v4.10.2 and v3.29.9 leaks excessive information into log

Impact

An information disclosure vulnerability in next-auth before v4.10.2 and v3.29.9 allows an attacker with log access privilege to obtain excessive information such as an identity provider’s secret in the log (which is thrown during OAuth error handling) and use it to leverage further attacks on the system, like impersonating the client to ask for extensive permissions.

Patches

We patched this vulnerability in v4.10.2 and v3.29.9 by moving the log for provider information to the debug level. In addition, we added a warning for having the debug: true option turned on in production and documented it here.
> You have enabled the debug option. It is meant for development only, to help you catch issues in your authentication flow and you should consider removing this option when deploying to production. One way of only allowing debugging while not in production is to set debug: process.env.NODE_ENV !== “production”, so you can commit this without needing to change the value.
>
> If you want to log debug messages during production anyway, we recommend setting the logger option with proper sanitization of potentially sensitive user information.

To upgrade:

npm i next-auth@latest
# or
yarn add next-auth@latest
# or
pnpm add next-auth@latest

(This will update to the latest v4 version, but you can change latest to 3 if you want to stay on v3. This is not recommended. v3 is unmaintained.)

Workarounds

If for some reason you cannot upgrade, you can user the logger configuration option by sanitizing the logs:

// Example
import log from "your-logging-service"
export const authOptions: NextAuthOptions = {
  debug: process.env.NODE_ENV !== "production",
  logger: {
    error: (code, metadata) => {
      if (!(metadata instanceof Error) &&  metadata.provider) {
        // redact the provider secret here
        delete metadata.provider
        log.error(code, metadata)
      } else {
        log.error(code, metadata)
      }
    }
  },
}

References

Related documentation:

• https://next-auth.js.org/warnings#debug_enabled
• https://next-auth.js.org/configuration/options#logger
• https://next-auth.js.org/getting-started/upgrade-v4

For more information

If you have any concerns, we request responsible disclosure, outlined here: https://next-auth.js.org/security#reporting-a-vulnerability

Timeline

The issue was reported 18th of July, a response was sent out in less than 20 minutes and after identifying the issue a patch was published within a week.