CSRF token fixation in fastify-passport
The CSRF protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport, can be bypassed by network and same-site attackers.
Details
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.
Fix
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.
Credits
- Pedro Adão (@pedromigueladao), Instituto Superior Técnico, University of Lisbon
- Marco Squarcina (@lavish), Security & Privacy Research Unit, TU Wien
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | @fastify/passport | < 1.1.0, >= 2.0.0, < 2.3.0 | 1.1.0, 2.3.0 |
References
- https://github.com/fastify/fastify-passport/security/advisories/GHSA-2ccf-ffrj-m4qw
- https://nvd.nist.gov/vuln/detail/CVE-2023-29020
- https://github.com/fastify/fastify-passport/commit/07c90feab9cba0dd4779e47cfb0717a7e2f01d3d
- https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html#synchronizer-token-pattern
- https://github.com/fastify/fastify-passport
- https://owasp.org/www-community/attacks/csrf
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N- Weakness (CWE)
CWE-352- Platform
- npm
- Package
@fastify/passport- Disclosed
- 21.04.2023
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-2ccf-ffrj-m4qw - CC BY 4.0
Vulnerability history: @fastify/passport
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 04.2023 04.2023
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 1
Disclosures per year
- 2023: 2
- 2024: 0
- 2025: 0
- 2026: 0
-
CSRF token fixation in fastify-passport this entry
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