CVE-2026-73421Network attack vector

Authentication bypass via truthy session error object

Published Aug 13, 2026 · Updated Aug 13, 2026

Improper authorization in NextAuth.js 5.0.0-beta.0 through 5.0.0-beta.31 allows remote attackers to access protected routes. The auth() wrapper parses a non-OK session response into a truthy error object rather than null, so bare auth-object existence checks pass. Exploitation requires a server configuration error and an application that treats auth-object existence alone as authentication; valid configurations are unaffected.

CVSS severity9.1
Critical
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authorization in NextAuth.js 5.0.0-beta.0 through 5.0.0-beta.31 allows remote attackers to access protected routes. The auth() wrapper parses a non-OK session response into a truthy error object rather than null, so bare auth-object existence checks pass. Exploitation requires a server configuration error and an application that treats auth-object existence alone as authentication; valid configurations are unaffected.

The record

CVE
CVE-2026-73421
Published
Aug 13, 2026
Updated
Aug 13, 2026
Vendor
Auth.js
Product
NextAuth.js
Classifications
CWE-285, CWE-636, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 5.0.0-beta.4, < 5.0.0-beta.32

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Auth.js · NextAuth.jsversion=>= 5.0.0-beta.4, < 5.0.0-beta.32

Published CVSS scores

9.1GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-285Improper Authorization
CWE-636Not Failing Securely ('Failing Open')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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