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CVE-2026-110008

MEDIUMCVSS 4.2/10

Last modified

CVE-2026-110008 is a medium-severity vulnerability rated 4.2/10 on the CVSS scale. @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.

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.

Metrics

CVSS 3.1
4.2/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
@fastify/oauth2@fastify/oauth2>= 7.2.0, < 8.3.2

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-110008?
@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.
How severe is CVE-2026-110008?
CVE-2026-110008 has a CVSS score of 4.2/10 (MEDIUM severity).
How do I fix CVE-2026-110008?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST