CVE-2026-55761

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. In versions 2.39.0 through 2.39.3 and 2.40.0 until 2.43.0, unauthenticated restore and administrator initialization endpoints (/api/restore and /api/users/admin/init) remain accessible during the five-minute setup window for uninitialized instances, allowing a network attacker to restore a crafted backup or create the first administrator account and gain full administrative access. This issue is fixed in versions 2.39.4 and 2.43.0.

Weakness Type (CWE)

CWE-287 Improper Authentication

References

Other References

https://github.com/portainer/portainer/commit/49f19107cf9a3540cbe406c9eb7f24390e1af02b https://github.com/portainer/portainer/commit/d2b56efcb4e43c4168bb6688eee9f6bf22867312 https://github.com/portainer/portainer/issues/2770 https://github.com/portainer/portainer/releases/tag/2.39.4 https://github.com/portainer/portainer/releases/tag/2.43.0 https://github.com/portainer/portainer/security/advisories/GHSA-x626-fcwx-f5pc

Frequently Asked Questions

What is CVE-2026-55761? +

Portainer Community Edition is a lightweight service delivery platform for containerized applications that can be used to manage Docker, Swarm, Kubernetes and ACI environments. In versions 2.39.0 through 2.39.3 and 2.40.0 until 2.43.0, unauthenticated restore and administrator initialization endpoints (/api/restore and /api/users/admin/init) remain accessible during the five-minute setup window for uninitialized instances, allowing a network attacker to restore a crafted backup or create the first administrator account and gain full administrative access. This issue is fixed in versions 2.39.4 and 2.43.0.

How do I check if I'm vulnerable to CVE-2026-55761? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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