Skip to content
Patch Next
Sign inAdd to your agent

← Actionable
High, CVSS 7.1amended

Portainer has Unauthenticated Restore Endpoint that Allows Admin Takeover on Uninitialized Instances

CVE-2026-55761GHSA-x626-fcwx-f5pc

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/portainer/portainer 2.43.0, 2.39.4), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

Add to your agent

Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
7.1 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:H · score source
EPSS
  • CVE-2026-55761: 0.49% estimated exploitation activity in the next 30 days; percentile 42.40 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Portainer supports restoring an instance from a backup archive via the /api/restore endpoint. This endpoint is intentionally unauthenticated to allow restoring before the first admin account is created, and remains accessible for the five-minute initialization window that opens each time Portainer starts. Any unauthenticated attacker with network access to a Portainer instance that has not yet been initialised can exploit this window to replace the Portainer database with a crafted archive containing attacker-controlled credentials and gain full administrative access. The same unauthenticated setup window also exposes the administrator-account-creation endpoint (/api/users/admin/init), which an attacker can call to create the first administrator directly; the fix gates both endpoints. The attack requires the instance to be uninitialized, reachable by the attacker, and within the five-minute window. Once that window expires without initialization, Portainer locks its API and…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 4 · amended ·

    Amended from ghsa record GHSA-x626-fcwx-f5pc

  2. Revision 3 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 2 · amended ·

    Amended from osv record GO-2026-6324

  4. Revision 1 · created ·

    Published from osv record GHSA-x626-fcwx-f5pc

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-55761

Advisory: Portainer has Unauthenticated Restore Endpoint that Allows Admin Takeover on Uninitialized Instances
IDs: CVE-2026-55761, GHSA-x626-fcwx-f5pc
Record: https://patchnext.com/advisories/cve-2026-55761 (revision 4, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/portainer/portainer 2.43.0, 2.39.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/portainer/portainer: affected >= 2.39.0, < 2.39.4; >= 2.40.0, < 2.43.0; fixed in 2.43.0, 2.39.4

## Suggested inspection (read-only)
- Go github.com/portainer/portainer: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/portainer/portainer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-x626-fcwx-f5pc (OSV record GHSA-x626-fcwx-f5pc lists affected ranges: Go github.com/portainer/portainer >=2.39.0 =2.40.0 <2.43.0 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6324 (OSV record GO-2026-6324 lists affected ranges: Go github.com/portainer/portainer >=0)
- Verified: https://github.com/advisories/GHSA-x626-fcwx-f5pc (GitHub-reviewed advisory GHSA-x626-fcwx-f5pc lists affected ranges: Go github.com/portainer/portainer >=2.39.0 =2.40.0 <2.43.0)

Commands are suggestions: review each one before running it.

Loading voting…