CSRF token fixation in fastify-passport

Description

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) and
  • clearSessionIgnoreFields (default: ['session'])

to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.

Credits

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
Open repository advisory ↗
Source code
Browse source ↗
Published (advisory)
2023-04-21 22:32:47 UTC
Updated
2023-11-09 05:00:59 UTC
GitHub reviewed
2023-04-21 22:32:47 UTC
NVD published
2023-04-21

EPSS Score

Score Percentile
0.08% 24.48%

CVSS Scores

Base score Version Severity Vector
6.5 3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

CWEs

CWE id Name
CWE-352 Cross-Site Request Forgery (CSRF)

Credits

  • pedromigueladao (reporter)
  • lavish (analyst)

Affected packages (2)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
npm @fastify/passport < 1.1.0 1.1.0
npm @fastify/passport >= 2.0.0, < 2.3.0 2.3.0

References

cvelogic Threat Intelligence