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CVE-2023-29020

Cross site request forgery token fixation in fastify-passport

6.5 MediumFix available

@fastify/passport is a port of passport authentication library for the Fastify ecosystem. The CSRF (Cross-Site Request Forger) protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport in affected versions, 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) and clearSessionIgnoreFields (default: ['passport', 'session']) to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
None

Exploit likelihood

0.38%Up 0.3 points since Apr 22, 2023
90%50%10%1%

What each source reports

CVE List Score used 6.5

Cross site request forgery token fixation in fastify-passport

@fastify/passport is a port of passport authentication library for the Fastify ecosystem. The CSRF (Cross-Site Request Forger) protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport in affected versions, 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) and clearSessionIgnoreFields (default: ['passport', 'session']) to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.

Record
CVE-2023-29020
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Weakness
CWE-384, CWE-352
Updated
2026-11-02
EUVDEUVD-2023-1154 6.5

@fastify/passport is a port of passport authentication library for the Fastify ecosystem. The CSRF (Cross-Site Request Forger) protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport in affected versions, 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) and clearSessionIgnoreFields (default: ['passport', 'session']) to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.

Record
EUVD-2023-1154
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-2ccf-ffrj-m4qw 6.5

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

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

Credits

Record
GHSA-2ccf-ffrj-m4qw
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Weakness
CWE-352
Updated
2026-11-02
NVD 6.5

@fastify/passport is a port of passport authentication library for the Fastify ecosystem. The CSRF (Cross-Site Request Forger) protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport in affected versions, 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) and clearSessionIgnoreFields (default: ['passport', 'session']) to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.

Record
CVE-2023-29020
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Weakness
CWE-352, CWE-384
Updated
2026-11-02
OSV 6.5

Cross site request forgery token fixation in fastify-passport

@fastify/passport is a port of passport authentication library for the Fastify ecosystem. The CSRF (Cross-Site Request Forger) protection enforced by the @fastify/csrf-protection library, when combined with @fastify/passport in affected versions, 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) and clearSessionIgnoreFields (default: ['passport', 'session']) to clear all the session attributes by default, preserving those explicitly defined in clearSessionIgnoreFields.

Record
CVE-2023-29020
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Weakness
CWE-352, CWE-384
Updated
2026-11-02
OSVGHSA-2ccf-ffrj-m4qw 6.5

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

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

Credits

Record
GHSA-2ccf-ffrj-m4qw
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Weakness
CWE-352
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
@fastify/passport
npm
before 1.1.0
1.1.0
@fastify/passport
npm
2.0.0 up to 2.3.0
2.3.0

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-29020 is a medium vulnerability (CVSS 6.5) in Fastify Fastify-passport, published April 21, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.38%, the 32nd percentile. Fixed in @fastify/passport 1.1.0.

References

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