CVE-2026-110008 @fastify/oauth2 vulnerable to Login CSRF via OAuth state cookie not cleared after callback
Attackers can perform login CSRF by reusing OAuth state cookies, allowing them to sign victims into attacker-controlled accounts.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-110008?
CVE-2026-110008 is a medium-severity vulnerability in @fastify/oauth2, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
@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.
Which versions are affected by CVE-2026-110008?
How do I fix CVE-2026-110008?
No fix has been published for CVE-2026-110008 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-110008 being exploited?
There is no known exploitation of CVE-2026-110008 in the wild and no public exploit code.
Sources
Also known as GHSA-7fcr-mwg4-pw9q.