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PatchSiren cyber security CVE debrief

CVE-2026-44884 portainer CVE debrief

Portainer Community Edition versions 2.33.0 through 2.33.7 and 2.39.0 contain a missing authorization vulnerability in the Custom Template file endpoint. The GET /api/custom_templates/{id}/file endpoint fails to enforce Resource Control access restrictions, allowing any authenticated user to read custom template file contents by enumerating sequential integer IDs. Custom template files may contain sensitive environment-specific values including connection strings, API tokens, and registry credentials that administrators expect to remain restricted to authorized users. The vulnerability was published on 2026-05-28.

Vendor
portainer
Product
Unknown
CVSS
MEDIUM 6
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-28
Original CVE updated
2026-07-21
Advisory published
2026-05-28
Advisory updated
2026-07-21

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.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-44884 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-44884

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

  • CVE-2026-44884 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-44884

    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.