{"id":"CVE-2023-29020","aliases":["GHSA-2ccf-ffrj-m4qw"],"url":"https://o3.security/vulnerability/CVE-2023-29020","summary":"Cross site request forgery token fixation in fastify-passport","details":"The [CSRF](https://owasp.org/www-community/attacks/csrf) protection enforced by the `@fastify/csrf-protection` library, when combined with `@fastify/passport`, can be bypassed by network and same-site attackers.\n\n## Details\n`fastify/csrf-protection` implements the [synchronizer token pattern](https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html#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.\n\nThe `@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](https://canitakeyoursubdomain.name/) 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.\n\n## Fix\nAs a solution, newer versions of `@fastify/passport` include the configuration options\n\n* `clearSessionOnLogin (default: true)` and\n* `clearSessionIgnoreFields (default: ['session'])`\n\nto clear all the session attributes by default, preserving those explicitly defined in `clearSessionIgnoreFields`.\n\n## Credits\n* Pedro Adão (@pedromigueladao), [Instituto Superior Técnico, University of Lisbon](https://tecnico.ulisboa.pt/)\n* Marco Squarcina (@lavish), [Security & Privacy Research Unit, TU Wien](https://secpriv.wien/)","published":"2023-04-21T22:31:56.768Z","modified":"2026-08-12T03:51:26.421545523Z","cvss":{"score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"npm","name":"@fastify/passport","fixedVersion":"1.1.0"},{"ecosystem":"npm","name":"@fastify/passport","fixedVersion":"2.3.0"}],"fix":{"url":"https://github.com/fastify/fastify-passport/commit/07c90feab9cba0dd4779e47cfb0717a7e2f01d3d","label":"fastify/fastify-passport@07c90fe"},"references":[{"type":"WEB","url":"https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html#synchronizer-token-pattern"},{"type":"WEB","url":"https://owasp.org/www-community/attacks/csrf"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/29xxx/CVE-2023-29020.json"},{"type":"ADVISORY","url":"https://github.com/fastify/fastify-passport/security/advisories/GHSA-2ccf-ffrj-m4qw"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-29020"},{"type":"FIX","url":"https://github.com/fastify/fastify-passport/commit/07c90feab9cba0dd4779e47cfb0717a7e2f01d3d"},{"type":"PACKAGE","url":"https://github.com/fastify/fastify-passport"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:26.421545523Z"}}