CVE-2026-43752: FileMaker Server Arbitrary Code Execution via LLM Upload

Technical summary

CVE-2026-43752 is an arbitrary code execution vulnerability affecting the Open Source LLM setup functionality in FileMaker Server's Admin Console. The flaw exists in the file upload mechanism, classified under CWE-434 (Unrestricted Upload of File with Dangerous Type). The CVSS 3.1 score of 4.9 reflects the requirement for elevated privileges (PR:H) but acknowledges the potential for confidentiality impact through code execution. The vulnerability allows an authenticated administrator to bypass upload restrictions and execute arbitrary commands with the privileges of the FileMaker Server process.

Business impact

Organizations running FileMaker Server rely on the platform for business-critical database and application services. Compromise of the host system through this vulnerability could lead to unauthorized access to sensitive data stored in FileMaker databases, disruption of services, lateral movement within the network, and potential data exfiltration. The confidentiality impact is rated high due to the attacker's ability to execute code and access system resources. However, the requirement for administrator-level authentication limits the attack surface to insider threats or compromised admin accounts.

Affected systems

FileMaker Server versions prior to 26.0.1 are affected. Organizations should immediately identify instances running older versions. The vulnerability is specific to the Admin Console interface and the Open Source LLM setup feature, meaning exposure is limited to systems with that functionality enabled.

Exploitability

Exploitation requires valid administrator credentials and network access to the FileMaker Server Admin Console. The attack is straightforward once authenticated—an attacker simply uploads a malicious file through the designated upload mechanism. No user interaction is required beyond the initial file submission. The low attack complexity (AC:L) and network accessibility (AV:N) make this relatively easy to exploit for those with admin access, but the high privilege requirement (PR:H) significantly restricts the threat actor pool to insiders, compromised admin accounts, or multi-stage attack scenarios.

Remediation

Upgrade FileMaker Server to version 26.0.1 or later immediately. This is a straightforward patching exercise. In the interim, organizations should restrict admin console access to trusted administrators, implement network segmentation to limit access to the Admin Console, and monitor for suspicious file uploads or unusual activity from admin accounts. Consider disabling the Open Source LLM setup feature if not actively used.

Patch guidance

Claris has released FileMaker Server 26.0.1 to address this vulnerability. Organizations should prioritize deployment of this patch, particularly in production environments. Before patching, review the Claris advisory for any compatibility notes, migration steps, or dependencies. Test patches in a staging environment first. Given the admin-level requirement, patching can often be scheduled during standard maintenance windows, though you should verify against your FileMaker deployment specifics and Claris release notes.

Detection guidance

Monitor FileMaker Server Admin Console logs for suspicious file uploads, particularly through the Open Source LLM setup feature. Look for unusual file types or naming patterns being uploaded. Audit admin account activity for unauthorized access or unexpected sessions, especially from non-standard IP addresses. Network intrusion detection systems should flag unusual POST requests to the Admin Console's upload endpoints. Additionally, track FileMaker Server version numbers across your infrastructure to identify unpatched instances.

Why prioritize this

While the CVSS score is moderate (4.9), the practical risk to many organizations is context-dependent. Organizations heavily dependent on FileMaker Server for critical operations should treat this as high priority due to potential for complete host compromise. However, the admin-level requirement significantly reduces urgency for organizations with strong access controls and trusted admin populations. Prioritize based on your FileMaker Server role in infrastructure, the sensitivity of data it hosts, and the trustworthiness of your admin user base.

Risk score, explained

The CVSS 3.1 score of 4.9 (MEDIUM) reflects a vulnerability with high confidentiality impact (C:H) but no impact to integrity or availability of the system itself. The critical mitigating factor is the requirement for high-level privileges (PR:H)—only administrators can exploit this. Network accessibility (AV:N) increases the score, as does low attack complexity. This scoring accurately captures that the vulnerability is serious for organizations facing insider threats or account compromise, but less critical for those with strong admin access controls.

Frequently asked questions