CVE-2023-48309: NextAuth.js provides authentication for Next.js. `next-auth` applications prior to version 4.24.5 that rely on the default Middleware authorization ar...

Description

NextAuth.js provides authentication for Next.js. `next-auth` applications prior to version 4.24.5 that rely on the default Middleware authorization are affected by a vulnerability. A bad actor could create an empty/mock user, by getting hold of a NextAuth.js-issued JWT from an interrupted OAuth sign-in flow (state, PKCE or nonce). Manually overriding the `next-auth.session-token` cookie value with this non-related JWT would let the user simulate a logged in user, albeit having no user information associated with it. (The only property on this user is an opaque randomly generated string). This vulnerability does not give access to other users' data, neither to resources that require proper authorization via scopes or other means. The created mock user has no information associated with it (ie. no name, email, access_token, etc.) This vulnerability can be exploited by bad actors to peek at logged in user states (e.g. dashboard layout). `next-auth` `v4.24.5` contains a patch for the vulnerability. As a workaround, using a custom authorization callback for Middleware, developers can manually do a basic authentication.

Metrics

CVSS 3.1

5.3/10

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

EPSS Probability

0.70%

48.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Nextauth.Js	Next-Auth	< 4.24.5

References

https://authjs.dev/guides/basics/role-based-access-controlTechnical Description
https://github.com/nextauthjs/next-auth/commit/d237059b6d0cb868c041ba18b698e0cee20a2f10Patch
https://github.com/nextauthjs/next-auth/security/advisories/GHSA-v64w-49xw-qq89Vendor Advisory
https://next-auth.js.org/configuration/nextjs#advanced-usageTechnical Description
https://next-auth.js.org/configuration/nextjs#middlewarTechnical Description
https://authjs.dev/guides/basics/role-based-access-controlTechnical Description
https://github.com/nextauthjs/next-auth/commit/d237059b6d0cb868c041ba18b698e0cee20a2f10Patch
https://github.com/nextauthjs/next-auth/security/advisories/GHSA-v64w-49xw-qq89Vendor Advisory
https://next-auth.js.org/configuration/nextjs#advanced-usageTechnical Description
https://next-auth.js.org/configuration/nextjs#middlewarTechnical Description

Timeline

Published: Nov 20, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-48309?

NextAuth.js provides authentication for Next.js. `next-auth` applications prior to version 4.24.5 that rely on the default Middleware authorization are affected by a vulnerability. A bad actor could create an empty/mock user, by getting hold of a NextAuth.js-issued JWT from an interrupted OAuth sign-in flow (state, PKCE or nonce). Manually overriding the `next-auth.session-token` cookie value with this non-related JWT would let the user simulate a logged in user, albeit having no user information associated with it. (The only property on this user is an opaque randomly generated string). This vulnerability does not give access to other users' data, neither to resources that require proper authorization via scopes or other means. The created mock user has no information associated with it (ie. no name, email, access_token, etc.) This vulnerability can be exploited by bad actors to peek at logged in user states (e.g. dashboard layout). `next-auth` `v4.24.5` contains a patch for the vulnerability. As a workaround, using a custom authorization callback for Middleware, developers can manually do a basic authentication.

How severe is CVE-2023-48309?

CVE-2023-48309 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.70% probability of exploitation in the next 30 days.

How do I fix CVE-2023-48309?

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.