CVE-2026-44882: Portainer Community Edition is a lightweight service delivery platform for containerized applications that can be used to manage Docker, Swarm, Kubern...

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.

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS Probability

0.34%

25.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-863

Affected Software

Vendor	Product	Versions
Portainer	Portainer	>= 2.33.0, < 2.33.8

References

https://github.com/portainer/portainer/security/advisories/GHSA-mgq6-4x29-88r3Exploit, Third Party Advisory

Timeline

Published: May 28, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-44882?

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.

How severe is CVE-2026-44882?

CVE-2026-44882 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.34% probability of exploitation in the next 30 days.

How do I fix CVE-2026-44882?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.