CVE-2026-39976Public exploitNetwork attack vector

User impersonation via unvalidated client subject lookup

Published Apr 9, 2026 · Updated Apr 9, 2026

Authentication bypass in Laravel Passport 13.0.0 through 13.7.0 allows remote authenticated users to impersonate unrelated users. TokenGuard passes the client identifier from a client_credentials token's subject claim to retrieveById() as though it identified a user, allowing an identifier collision or database conversion to resolve a real account. Exploitation requires a valid machine-to-machine token and an application whose user lookup resolves that client subject to a user record, exposing that account's data and permissions.

CVSS severity7.1
High
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Laravel Passport 13.0.0 through 13.7.0 allows remote authenticated users to impersonate unrelated users. TokenGuard passes the client identifier from a client_credentials token's subject claim to retrieveById() as though it identified a user, allowing an identifier collision or database conversion to resolve a real account. Exploitation requires a valid machine-to-machine token and an application whose user lookup resolves that client subject to a user record, exposing that account's data and permissions.

The record

CVE
CVE-2026-39976
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Laravel
Product
Laravel Passport
Classifications
CWE-287, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 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=>= 13.0.0, < 13.7.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Laravel · Laravel Passportversion=>= 13.0.0, < 13.7.1

Published CVSS scores

7.1GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A: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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-287Improper Authentication
T1190Exploit Public-Facing Application

Public exploit references

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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