{"id":"CVE-2023-31999","aliases":["GHSA-g8x5-p9qc-cf95"],"url":"https://o3.security/vulnerability/CVE-2023-31999","summary":"@fastify/oauth2 vulnerable to Cross Site Request Forgery due to reused Oauth2 state","details":"### Impact\n\nAll versions of @fastify/oauth2 used a statically generated `state` parameter at startup time and were used across all requests for all users.\nThe purpose of the Oauth2 `state` parameter is to prevent Cross-Site-Request-Forgery attacks. As such, it should be unique per user and should be connected to the user's session in some way that will allow the server to validate it.\n\n### Patches\n\nv7.2.0 changes the default behavior to store the `state` in a cookie with the `http-only` and `same-site=lax` attributes set. The state is now by default generated for every user.\n\nNote that this contains a breaking change in the `checkStateFunction` function, which now accepts the full `Request` object.\n\n### Workarounds\n\nThere are no known workarounds.\n\n### References\n\n* [Prevent Attacks and Redirect Users with OAuth 2.0 State Parameters](https://auth0.com/docs/secure/attack-protection/state-parameters)\n","published":"2023-07-04T16:29:20.281Z","modified":"2026-08-12T03:51:21.823626347Z","cvss":{"score":7.4,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":1,"affectedPackages":[{"ecosystem":"npm","name":"@fastify/oauth2","fixedVersion":"7.2.0"}],"fix":{"url":"https://github.com/fastify/fastify-oauth2/commit/bff756b456cbb769080631af2beb85671ff4c79c","label":"fastify/fastify-oauth2@bff756b"},"references":[{"type":"WEB","url":"https://auth0.com/docs/secure/attack-protection/state-parameters"},{"type":"WEB","url":"https://github.com/fastify/fastify-oauth2/releases/tag/v7.2.0"},{"type":"WEB","url":"https://hackerone.com/reports/2020418"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/31xxx/CVE-2023-31999.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-31999"},{"type":"WEB","url":"https://github.com/fastify/fastify-oauth2/security/advisories/GHSA-g8x5-p9qc-cf95"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2023-35935"},{"type":"WEB","url":"https://github.com/fastify/fastify-oauth2/commit/bff756b456cbb769080631af2beb85671ff4c79c"},{"type":"PACKAGE","url":"https://github.com/fastify/fastify-oauth2"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:21.823626347Z"}}