CVE-2026-23998
Fleet has a Windows MDM management endpoint authentication bypass
Description
Fleet is open source device management software. Prior to version 4.81.0, a vulnerability in Fleet’s Windows MDM management endpoint could allow requests to be processed without proper client certificate validation. In certain circumstances, this could allow an attacker to impersonate an enrolled Windows device and retrieve sensitive configuration data. Fleet’s Windows MDM management endpoint relies on mutual TLS (mTLS) client certificates to authenticate enrolled devices. In affected versions, requests that did not present a client certificate could be incorrectly treated as trusted. As a result, an attacker with prior knowledge of a valid enrolled device identifier could potentially impersonate that device and receive configuration payloads intended for it. These payloads may contain sensitive information such as Wi-Fi or VPN configuration data, certificates, or other secrets delivered through MDM profiles. This issue does not allow enrollment of new devices, administrative access to Fleet, or compromise of the Fleet control plane. Impact is limited to the targeted Windows device. Version 4.81.0 contains a patch. If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.
INFO
Published Date :
May 14, 2026, 7:16 p.m.
Last Modified :
Oct. 26, 2026, 2:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Upgrade Fleet to version 4.81.0 or newer.
- Temporarily disable Windows MDM if upgrade is not immediate.
- Ensure client certificate validation is properly configured.
- Monitor for unauthorized device impersonation attempts.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-23998.
| URL | Resource |
|---|---|
| https://github.com/fleetdm/fleet/releases/tag/fleet-v4.81.0 | Product Release Notes |
| https://github.com/fleetdm/fleet/security/advisories/GHSA-2rc4-7jc6-qffh | Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-23998 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-23998
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-23998 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-23998 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: fleet de fleetdm, Description: Fleet es un software de gestión de dispositivos de código abierto. Antes de la versión 4.81.0, una vulnerabilidad en el endpoint de gestión MDM de Windows de Fleet podría permitir que las solicitudes se procesaran sin la validación adecuada del certificado del cliente. En ciertas circunstancias, esto podría permitir a un atacante suplantar la identidad de un dispositivo Windows registrado y recuperar datos de configuración sensibles. El endpoint de gestión MDM de Windows de Fleet se basa en certificados de cliente TLS mutuo (mTLS) para autenticar dispositivos registrados. En las versiones afectadas, las solicitudes que no presentaban un certificado de cliente podrían ser tratadas incorrectamente como de confianza. Como resultado, un atacante con conocimiento previo de un identificador de dispositivo registrado válido podría potencialmente suplantar la identidad de ese dispositivo y recibir cargas útiles de configuración destinadas a él. Estas cargas útiles pueden contener información sensible como datos de configuración de Wi-Fi o VPN, certificados u otros secretos entregados a través de perfiles MDM. Este problema no permite el registro de nuevos dispositivos, el acceso administrativo a Fleet, o el compromiso del plano de control de Fleet. El impacto se limita al dispositivo Windows objetivo. La versión 4.81.0 contiene un parche. Si una actualización inmediata no es posible, los usuarios afectados de Fleet deberían deshabilitar temporalmente el MDM de Windows. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'fleetdm', 'product': 'fleet', 'versions': [{'status': 'affected', 'version': '< 4.81.0'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-23998', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-05-15T14:12:42.598363Z'} -
Initial Analysis by [email protected]
May. 15, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Added CPE Configuration OR *cpe:2.3:a:fleetdm:fleet:*:*:*:*:*:*:*:* versions up to (excluding) 4.81.0 Added Reference Type GitHub, Inc.: https://github.com/fleetdm/fleet/releases/tag/fleet-v4.81.0 Types: Product, Release Notes Added Reference Type GitHub, Inc.: https://github.com/fleetdm/fleet/security/advisories/GHSA-2rc4-7jc6-qffh Types: Mitigation, Vendor Advisory -
New CVE Received by [email protected]
May. 14, 2026
Action Type Old Value New Value Added Description Fleet is open source device management software. Prior to version 4.81.0, a vulnerability in Fleet’s Windows MDM management endpoint could allow requests to be processed without proper client certificate validation. In certain circumstances, this could allow an attacker to impersonate an enrolled Windows device and retrieve sensitive configuration data. Fleet’s Windows MDM management endpoint relies on mutual TLS (mTLS) client certificates to authenticate enrolled devices. In affected versions, requests that did not present a client certificate could be incorrectly treated as trusted. As a result, an attacker with prior knowledge of a valid enrolled device identifier could potentially impersonate that device and receive configuration payloads intended for it. These payloads may contain sensitive information such as Wi-Fi or VPN configuration data, certificates, or other secrets delivered through MDM profiles. This issue does not allow enrollment of new devices, administrative access to Fleet, or compromise of the Fleet control plane. Impact is limited to the targeted Windows device. Version 4.81.0 contains a patch. If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM. Added CVSS V4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/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:X/V:X/RE:X/U:X Added CWE CWE-295 Added Reference https://github.com/fleetdm/fleet/releases/tag/fleet-v4.81.0 Added Reference https://github.com/fleetdm/fleet/security/advisories/GHSA-2rc4-7jc6-qffh