The CSRF protection enforced by the @fastify/csrf-protection
library, when combined with @fastify/passport
, can be bypassed by network and same-site attackers.
fastify/csrf-protection
implements the synchronizer token pattern (using plugins @fastify/session
and @fastify/secure-session
) by storing a random value used for CSRF token generation in the _csrf
attribute of a user's session.
The @fastify/passport
library does not clear the session object upon authentication, preserving the _csrf
attribute between pre-login and authenticated sessions. Consequently, CSRF tokens generated before authentication are still valid. Network and same-site attackers can thus obtain a CSRF token for their pre-session, fixate that pre-session in the victim's browser via cookie tossing, and then perform a CSRF attack after the victim authenticates.
As a solution, newer versions of @fastify/passport
include the configuration options
clearSessionOnLogin (default: true)
andclearSessionIgnoreFields (default: ['session'])
to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields
.
{ "cwe_ids": [ "CWE-352" ], "nvd_published_at": "2023-04-21T23:15:20Z", "github_reviewed_at": "2023-04-21T22:32:47Z", "github_reviewed": true, "severity": "MODERATE" }