---
id: CVE-2026-110008
title: >-
  @fastify/oauth2 vulnerable to Login CSRF via OAuth state cookie not cleared
  after callback
summary: >-
  @fastify/oauth2 is a Fastify wrapper for OAuth2 login flows. In versions 7.2.0
  through 8.3.1, the state and code-verifier cookies are set without a Path
  attribute at a login route with two or more path segments, while the clearing
  step a…
severity: medium
cvss: 4.2
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N'
cvssSource: cna
cwe:
  - CWE-352
  - CWE-459
  - CWE-613
vendor: '@fastify/oauth2'
product: '@fastify/oauth2'
affected:
  - '@fastify/oauth2 >= 7.2.0 < 8.3.2'
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-19T14:26:36.141774Z'
published: '2026-10-19'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T14:26:45.991Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-110008'
references:
  - url: >-
      https://github.com/fastify/fastify-oauth2/security/advisories/GHSA-7fcr-mwg4-pw9q
  - url: 'https://cna.openjsf.org/security-advisories.html'
tags:
  - cve.org
ingestedAt: '2026-10-19T13:28:55.890Z'
---

## Overview

@fastify/oauth2 is a Fastify wrapper for OAuth2 login flows. In versions 7.2.0 through 8.3.1, the state and code-verifier cookies are set without a Path attribute at a login route with two or more path segments, while the clearing step at the OAuth callback writes them with a root path, so the original cookies survive the callback and the documented single-use guarantee for the state value does not hold. A state value an attacker learns stays valid for the rest of the browser session, letting the attacker drive their own authorization flow in the victim's browser and sign the victim in to the attacker's account (login CSRF). The issue is fixed in @fastify/oauth2 8.3.2, and users should upgrade to 8.3.2 or later. As a workaround, set an explicit cookie path so the set and the clear name the same cookie.

## Affected

- `@fastify/oauth2 >= 7.2.0 < 8.3.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.