CVE-2023-29019: Fastify Passport

High severity, CVSS 8.1. EPSS: 0.8% chance of exploitation in the next 30 days.

@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.

Affected products

• Fastify Passport: before 1.1.0 (fixed in 1.1.0); from 2.0.0, before 2.3.0 (fixed in 2.3.0)

Published 2023-04-21. Last modified 2026-06-17.