Session fixation in fastify-passport

Vulnerability Description

@fastify/passport is a port of passport authentication library for the Fastify ecosystem. Applications using `@fastify/passport` in affected versions for user authentication, in combination with `@fastify/session` as the underlying session management mechanism, are vulnerable to session fixation attacks from network and same-site attackers. fastify applications rely on the `@fastify/passport` library for user authentication. The login and user validation are performed by the `authenticate` function. When executing this function, the `sessionId` is preserved between the pre-login and the authenticated session. Network and same-site attackers can hijack the victim's session by tossing a valid `sessionId` cookie in the victim's browser and waiting for the victim to log in on the website. As a solution, newer versions of `@fastify/passport` regenerate `sessionId` upon login, preventing the attacker-controlled pre-session cookie from being upgraded to an authenticated session. Users are advised to upgrade. There are no known workarounds for this vulnerability.

References

• https://github.com/fastify/fastify-passport/security/advisories/GHSA-4m3m-ppvx-xgw9
• https://github.com/fastify/fastify-passport/commit/43c82c321db58ea3e375dd475de60befbfcf2a11
• https://owasp.org/www-community/attacks/Session_fixation