Can this vulnerability be exploited remotely?

Yes. Any party that can obtain a valid `client_credentials` token against the affected Laravel Passport deployment and reach protected endpoints over the network can potentially trigger this issue, depending on how identifiers are stored and resolved.

Does an attacker need user credentials to exploit this?

No direct user credentials are required. The key requirement is the ability to authenticate as an OAuth client and obtain a `client_credentials` token; from there, the ambiguity in subject handling may allow the token to be treated as a user.

What is the safest general fix pattern?

Enforce strict separation between client and user identities in your authentication layer. Ensure the token guard does not treat `client_credentials` tokens as user tokens, and only resolve users from tokens whose grant type and claims unambiguously represent an end user.

Severity:

HIGH RISK

(7.1)

Authentication Bypass via Misused JWT Subject (CWE-287) in Laravel Passport OAuth2 Guard

CVE-2026-39976

Published:

Apr 9, 2026

Status:

Awaiting Analysis

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

NDV

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Vulnerability Type

Category:

Authentication Bypass

CWE:

CWE-287

Impact:

Improper User Authentication / Privilege Confusion

Severity:

HIGH RISK

(7.1)

CVSS Version:

3.1

Vulnerability Type

Category:

Authentication Bypass

CWE:

CWE-287

Impact:

Improper User Authentication / Privilege Confusion

Severity:

HIGH RISK

(7.1)

CVSS Version:

3.1

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Authentication Bypass via Misused JWT Subject (CWE-287) in Laravel Passport OAuth2 Guard

Summary

Affected Context

Exploit Preconditions

Why This Happens

Potential Impact

General Mitigation Guidance

How Teams Detect Issues Like This

Frequently Asked Questions

Source

Recent Vulnerabilities

HIGH RISK

HIGH

(8.8)

PHP Code Injection via File Upload (CWE-94) in Aero CMS Admin Post Creation

HIGH RISK

HIGH

(8.8)

Code Injection (CWE-94) via Module Parameters in Evolution CMS

Vulnerability Type

Vulnerability Type

Vulnerability Type

Catch This CVE While Code Is Being Written

Ship clean & secure code faster

Ship clean & secure code faster

Ship clean & secure code faster

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