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Vulnerability record · CVE-2026-73421 · published 13 August 2026

CVE-2026-73421: Improper authorization vulnerability

NextAuth.js provides authentication for Next.js. From next-auth 5.0.0-beta.0 until 5.0.0-beta.32, applications that gate access by checking only for the existence of the auth object returned by the auth() wrapper can fail open when Auth.js has a server configuration error. In middleware, Route Handlers, React Server Components, and other auth() entry points, a non-OK session response is parsed into a truthy error object instead of null, so checks such as !!auth and if (req.auth) evaluate to true for unauthenticated requests. A provider missing both the issuer and authorization endpoint triggers InvalidEndpoints, and an unset AUTH_SECRET or another server configuration error can produce the same behavior. There is no impact while configuration is valid, but after a deployment becomes misconfigured, routes protected only by session existence silently grant access to every visitor. This issue is fixed in next-auth 5.0.0-beta.32.

9.1 CVSS 4.0 Critical EPSS 0.64% · top 51.3% CWE-285 · Improper authorizationCWE-636 · CWE-636 Awaiting Analysis
9.1CVSS 4.0 base score
0.64%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
18 Sep 2026Last modified by NVD

Description

NextAuth.js provides authentication for Next.js. From next-auth 5.0.0-beta.0 until 5.0.0-beta.32, applications that gate access by checking only for the existence of the auth object returned by the auth() wrapper can fail open when Auth.js has a server configuration error. In middleware, Route Handlers, React Server Components, and other auth() entry points, a non-OK session response is parsed into a truthy error object instead of null, so checks such as !!auth and if (req.auth) evaluate to true for unauthenticated requests. A provider missing both the issuer and authorization endpoint triggers InvalidEndpoints, and an unset AUTH_SECRET or another server configuration error can produce the same behavior. There is no impact while configuration is valid, but after a deployment becomes misconfigured, routes protected only by session existence silently grant access to every visitor. This issue is fixed in next-auth 5.0.0-beta.32.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/nextauthjs/next-auth/commit/d008b9b764bf4b322a87e1822d1dda7789258d8f
https://github.com/nextauthjs/next-auth/releases/tag/[email protected]
https://github.com/nextauthjs/next-auth/security/advisories/GHSA-8fpg-xm3f-6cx3

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Source: NIST National Vulnerability Database (record CVE-2026-73421), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.