CVE-2026-55761 Portainer: Unauthenticated Restore Endpoint Allows Admin Takeover on Uninitialised Portainer Instances

What is CVE-2026-55761?

CVE-2026-55761 is a high-severity authentication bypass vulnerability in portainer, published on 8 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official 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: CWE-287

Which versions are affected by CVE-2026-55761?

5 open source packages ship an affected version, including github.com/portainer/portainer. It affects 1 product.

Products include Portainer Portainer.

How do I fix CVE-2026-55761?

Upgrade github.com/portainer/portainer to a fixed version for your release line: 2.39.4 or 2.43.0.

Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.

Is CVE-2026-55761 being exploited?

There is no known exploitation of CVE-2026-55761 in the wild and no public exploit code.

Other vulnerabilities in portainer

• CVE-2019-16872 Missing authorization in n/a Critical 9.9
• CVE-2022-24961 Missing authorization in n/a Critical 9.8
• CVE-2020-24264 Missing authorization in n/a Critical 9.8
• CVE-2018-19466 Information disclosure in n/a Critical 9.8
• CVE-2018-19367 Auth bypass in n/a Critical 9.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-x626-fcwx-f5pc, GO-2026-6324.