CVE-2026-44884 portainer CVE debrief

Who should care

Organizations running Portainer Community Edition 2.33.0-2.33.7 or 2.39.0 for container orchestration, particularly those using custom templates with embedded credentials or multi-tenant deployments where template access should be restricted by team or user boundaries.

Technical summary

The vulnerability exists in the Custom Template file retrieval endpoint where resource ownership validation is insufficient. An authenticated attacker can iterate through integer ID values to access template files belonging to other users or teams, bypassing intended access controls. The endpoint returns raw file contents which may include hardcoded secrets, infrastructure credentials, or proprietary configuration data. This represents a classic insecure direct object reference (IDOR) pattern within an authenticated context.

Defensive priority

medium

Recommended defensive actions

• Upgrade Portainer Community Edition to version 2.33.8 or 2.39.1 or later
• Review custom template files for exposed sensitive values and rotate any potentially compromised credentials
• Audit access logs for unusual enumeration patterns against the /api/custom_templates/{id}/file endpoint
• Implement network segmentation to limit Portainer administrative interface exposure
• Review and strengthen Resource Control policies for custom templates to ensure least-privilege access

Evidence notes

The vulnerability description confirms the affected endpoint (GET /api/custom_templates/{id}/file) and the IDOR-style attack vector through sequential integer enumeration. CVSS 4.0 vector indicates network attack vector, low attack complexity, privileged access required (authenticated user), and high confidentiality impact to the vulnerable component.

Official resources