CVE-2026-40425: MacGregor VDR Admin File Access Vulnerability – MEDIUM Risk

Technical summary

CVE-2026-40425 involves improper restriction of file access permissions in the MacGregor Interschalt VDR G4E firmware. The vulnerability is rooted in CWE-552 (Files or Directories Accessible to External Parties), allowing the web interface administrator account to directly edit files that control authentication mechanisms. An authenticated admin user can manipulate these sensitive files to change the root password or modify other authentication controls, bypassing normal administrative approval workflows. The CVSS 3.1 score of 5.7 (MEDIUM) reflects the requirement for high-privilege account access but acknowledges the high confidentiality impact and potential for lateral privilege escalation within the device ecosystem.

Business impact

For maritime operators and vessel management organizations, this vulnerability could allow a rogue or compromised administrator account to lock out legitimate system operators and establish persistent unauthorized access. Voyage Data Recorders are critical safety and compliance systems; unauthorized root-level access could compromise data integrity, audit trails, or system availability during critical maritime operations. Organizations may face regulatory scrutiny if VDR authentication controls are circumvented, and the potential for sabotage or data tampering poses operational and liability risks.

Affected systems

This vulnerability affects MacGregor Interschalt VDR G4E devices running affected firmware versions. Specifically impacted products are macgregor interschalt_vdr_g4e and macgregor interschalt_vdr_g4e_firmware. Organizations operating these Voyage Data Recorder units should verify their current firmware version against vendor advisories and assess whether their systems are running vulnerable releases.

Exploitability

Exploitation requires valid administrator credentials for the web interface, limiting the attack surface to insider threats or compromised admin accounts. An attacker cannot exploit this vulnerability without already possessing high-privilege access to the system. However, once authenticated as an admin, the exploitation steps are straightforward and do not require bypassing additional security controls or user interaction. The vulnerability does not appear on CISA's Known Exploited Vulnerabilities (KEV) catalog, and no public exploit code has been documented at this time.

Remediation

Vendors have issued firmware updates to restrict administrative file modification capabilities and properly enforce access controls on sensitive authentication files. Organizations should apply the latest available firmware patch from MacGregor and verify that the updated version properly restricts file access to prevent unauthorized credential modification. If immediate patching is not feasible, administrators should implement strict access controls on the VDR web interface and conduct regular audits of authentication file integrity.

Patch guidance

Consult the official MacGregor security advisory for the specific firmware version numbers that remediate this issue. Prioritize deployment of patched firmware to all affected VDR G4E units. Testing should include verification that administrative users can no longer directly edit authentication-sensitive files through the web interface. Document the patch version applied and maintain audit logs of the update process. If your organization uses a fleet management system, coordinate updates to minimize operational disruption.

Detection guidance

Monitor web server logs for the VDR device for unusual administrative activity, particularly file access or modification events related to authentication configuration files (e.g., password files, authentication-related configuration). Implement file integrity monitoring (FIM) on sensitive system files, especially those controlling root user credentials. Alert on any modifications to these files outside of standard maintenance windows. Regular audits of the root password hash and administrative user accounts can identify unauthorized changes. Network-based detection should flag suspicious administrative login sessions followed by system-level file operations.

Why prioritize this

Although this is a MEDIUM-severity vulnerability requiring existing administrative credentials, the potential for privilege escalation and root password compromise warrants timely attention. Voyage Data Recorders are safety-critical systems with strict regulatory compliance requirements, making authentication integrity essential. The vulnerability is relatively straightforward to exploit for anyone with admin access, creating insider threat and supply-chain compromise risks. Organizations should patch within the next 60–90 days, prioritizing vessels or systems with higher user turnover or external admin access.

Risk score, explained

The CVSS 3.1 score of 5.7 reflects the attack vector requiring proximity or network access (AV:A), low attack complexity (AC:L), and high privilege requirement (PR:H). The high confidentiality impact (C:H) and limited integrity and availability impacts (I:L, A:L) result from the ability to change authentication credentials and potentially disrupt system operations. The score appropriately recognizes that exploitation requires existing admin privilege but flags the serious downstream consequences of root credential compromise.

Frequently asked questions