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CVE-2026-55761 portainer CVE debrief

CVE-2026-55761 is a high severity vulnerability in Portainer Community Edition, a lightweight service delivery platform for containerized applications. The issue allows unauthenticated access to restore and administrator initialization endpoints during the five-minute setup window for uninitialized instances. This vulnerability affects users of Portainer Community Edition versions 2.39.0 through 2.39.3 and 2.40.0 until 2.43.0. The vulnerability has a high CVSS score of 7.1 and is considered a significant risk.

Vendor
portainer
Product
Unknown
CVSS
HIGH 7.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-08
Original CVE updated
2026-07-10
Advisory published
2026-07-08
Advisory updated
2026-07-10

Who should care

Users of Portainer Community Edition versions 2.39.0 through 2.39.3 and 2.40.0 until 2.43.0 should apply patches or mitigations. This includes operators, platform administrators, vulnerability management teams, and security teams who are responsible for ensuring the security and integrity of their systems.

Technical summary

Portainer Community Edition has a vulnerability allowing unauthenticated restore and administrator initialization. This issue exists in versions 2.39.0 through 2.39.3 and 2.40.0 until 2.43.0. The vulnerability is caused by the lack of authentication required for the restore and administrator initialization endpoints during the five-minute setup window for uninitialized instances. This allows a network attacker to restore a crafted backup or create the first administrator account and gain full administrative access.

Defensive priority

Apply patches or mitigations for Portainer Community Edition versions 2.39.0 through 2.39.3 and 2.40.0 until 2.43.0.

Recommended defensive actions

  • Apply patches or mitigations for Portainer Community Edition versions 2.39.0 through 2.39.3 and 2.40.0 until 2.43.0.
  • Restrict access to the five-minute setup window for uninitialized instances.
  • Monitor for suspicious activity on Portainer Community Edition instances.
  • Review compensating controls for exposed systems while remediation is scheduled and verified.
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review.
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented.
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.

Evidence notes

The CVE record was published on 2026-07-08T16:16:31.020Z and was last modified on 2026-07-10T17:48:26.790Z. The evidence is limited to the information provided in the CVE record and NVD detail. Defenders should verify the affected scope, severity, and vendor guidance. The CVE record and NVD detail provide the most up-to-date information on this vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-55761 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-55761

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-55761 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-55761

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.