CVE-2026-44882
Portainer: Kubernetes middleware continues after token validation failure, bypassing endpoint authorization
Description
Portainer Community Edition is a lightweight service delivery platform for containerized applications that can be used to manage Docker, Swarm, Kubernetes and ACI environments. From 2.33.0 to before 2.33., Portainer proxies requests to Kubernetes clusters through a middleware layer (kubeClientMiddleware) that validates the requesting user's token before forwarding traffic to the cluster. When security.RetrieveTokenData returned an error, the middleware wrote an HTTP 403 response but was missing a return statement — execution continued into the handler with a nil tokenData value. The Kubernetes endpoints sit behind Portainer's outer AuthenticatedAccess bouncer, so an attacker requires a valid Portainer session. However, a user whose secondary token validation fails in kubeClientMiddleware — for example a user without permission to access a given Kubernetes endpoint — would have their request forwarded to the cluster anyway, bypassing the authorization check. The same defect was present in both the CE and EE codebases. This vulnerability is fixed in 2.33.8.
INFO
Published Date :
May 28, 2026, 10:16 p.m.
Last Modified :
July 21, 2026, 10:10 a.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 3.1 | HIGH | MITRE-CVE |
Solution
- Update Portainer Community Edition to version 2.33.8.
- Apply vendor security patches promptly.
- Validate user access to Kubernetes endpoints.
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-2026-44882.
| URL | Resource |
|---|---|
| https://github.com/portainer/portainer/security/advisories/GHSA-mgq6-4x29-88r3 | Exploit Third Party 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-2026-44882 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-2026-44882
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-2026-44882 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-44882 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]
Jul. 21, 2026
Action Type Old Value New Value Added Translation Title: Portainer Community Edition, Description: Portainer Community Edition es una plataforma ligera de entrega de servicios para aplicaciones en contenedores que puede utilizarse para gestionar entornos Docker, Swarm, Kubernetes y ACI. Desde la 2.33.0 hasta antes de la 2.33., Portainer actúa como proxy para las solicitudes a los clústeres de Kubernetes a través de una capa de middleware (kubeClientMiddleware) que valida el token del usuario solicitante antes de reenviar el tráfico al clúster. Cuando security.RetrieveTokenData devolvía un error, el middleware escribía una respuesta HTTP 403 pero faltaba una sentencia de retorno — la ejecución continuaba en el gestor con un valor tokenData nulo. Los puntos finales de Kubernetes se encuentran detrás del bouncer externo AuthenticatedAccess de Portainer, por lo que un atacante requiere una sesión válida de Portainer. Sin embargo, un usuario cuya validación de token secundaria falla en kubeClientMiddleware — por ejemplo, un usuario sin permiso para acceder a un punto final de Kubernetes determinado — vería su solicitud reenviada al clúster de todos modos, omitiendo la comprobación de autorización. El mismo defecto estaba presente tanto en las bases de código CE como EE. Esta vulnerabilidad está corregida en la 2.33.8. -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'portainer', 'product': 'portainer', 'versions': [{'status': 'affected', 'version': '>= 2.33.0, < 2.33.8'}]}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-44882', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-05-30T02:20:34.739258Z'} -
Initial Analysis by [email protected]
Jun. 01, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:portainer:portainer:*:*:*:*:community:*:*:* versions from (including) 2.33.0 up to (excluding) 2.33.8 Added Reference Type GitHub, Inc.: https://github.com/portainer/portainer/security/advisories/GHSA-mgq6-4x29-88r3 Types: Exploit, Third Party Advisory -
New CVE Received by [email protected]
May. 28, 2026
Action Type Old Value New Value Added Description Portainer Community Edition is a lightweight service delivery platform for containerized applications that can be used to manage Docker, Swarm, Kubernetes and ACI environments. From 2.33.0 to before 2.33., Portainer proxies requests to Kubernetes clusters through a middleware layer (kubeClientMiddleware) that validates the requesting user's token before forwarding traffic to the cluster. When security.RetrieveTokenData returned an error, the middleware wrote an HTTP 403 response but was missing a return statement — execution continued into the handler with a nil tokenData value. The Kubernetes endpoints sit behind Portainer's outer AuthenticatedAccess bouncer, so an attacker requires a valid Portainer session. However, a user whose secondary token validation fails in kubeClientMiddleware — for example a user without permission to access a given Kubernetes endpoint — would have their request forwarded to the cluster anyway, bypassing the authorization check. The same defect was present in both the CE and EE codebases. This vulnerability is fixed in 2.33.8. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-863 Added Reference https://github.com/portainer/portainer/security/advisories/GHSA-mgq6-4x29-88r3