# CVE-2026-73421

## Summary

- **CVE ID:** CVE-2026-73421
- **Severity:** CRITICAL
- **CVSS Score:** 9.1 (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)
- **CWE:** CWE-285, CWE-636
- **Published:** Aug 13, 2026
- **Last Modified:** Aug 18, 2026

## 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.

## Affected Products

- nextauthjs — next-auth (>= 5.0.0-beta.4, < 5.0.0-beta.32)

## References

- [CNA](https://github.com/nextauthjs/next-auth/security/advisories/GHSA-8fpg-xm3f-6cx3)
- [CNA](https://github.com/nextauthjs/next-auth/commit/d008b9b764bf4b322a87e1822d1dda7789258d8f)
- [CNA](https://github.com/nextauthjs/next-auth/releases/tag/next-auth@5.0.0-beta.32)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.46%
- **EPSS Percentile:** 38.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-11._