Fortinet FortiWeb Fabric Connector Vulnerability Exploited to Execute Remote Code

A critical security vulnerability in Fortinet’s FortiWeb Fabric Connector has been discovered and exploited, allowing attackers to execute remote code on affected systems without authentication.

The vulnerability, designated CVE-2025-25257, represents a significant threat to organizations using Fortinet’s web application firewall solutions.

Key Takeaways
1. Fortinet FortiWeb Fabric Connector has an unauthenticated SQL injection (CVE-2025-25257) enabling remote code execution.
2. Impacts FortiWeb 7.0.0-7.0.10, 7.2.0-7.2.10, 7.4.0-7.4.7, 7.6.0-7.6.3; patch by upgrading to 7.0.11, 7.2.11, 7.4.8, or 7.6.4.
3. Attackers can bypass authentication, gain root access, and execute code via malicious file writes.
4. Apply patches, restrict API access, and monitor for suspicious activity to prevent compromise.

The vulnerability stems from an unauthenticated SQL injection flaw in the FortiWeb Fabric Connector’s authentication mechanism.

This connector serves as integration middleware between FortiWeb web application firewalls and other Fortinet ecosystem products, enabling dynamic policy updates based on real-time infrastructure changes and threat intelligence.

CVE-2025-25257 affects multiple versions of FortiWeb, including versions 7.0.0 through 7.0.10, 7.2.0 through 7.2.10, 7.4.0 through 7.4.7, and 7.6.0 through 7.6.3. Fortinet has released patches requiring upgrades to versions 7.0.11, 7.2.11, 7.4.8, and 7.6.4, respectively.

Fortinet FortiWeb Fabric Connector Vulnerability

Watchtower researchers analyzing the vulnerability discovered that the flaw resides in the get_fabric_user_by_token function, which processes authentication tokens from external Fortinet devices attempting to integrate with FortiWeb APIs.

The function improperly constructs SQL queries by directly inserting user-controlled input without sanitization or parameterized statements.

The vulnerable code uses a simple snprintf function to build queries like select id from fabric_user.user_table where token='%s', where the token value comes directly from HTTP Authorization headers.

This classic SQL injection vulnerability can be exploited through specially crafted Bearer tokens in API requests to endpoints such as /api/fabric/device/status.

Exploitation requires understanding the input constraints imposed by the sscanf function, which stops parsing at the first space character and limits input to 128 characters.

Attackers can bypass these restrictions using MySQL comment syntax (/**/) to replace spaces and carefully crafted payloads that fit within the character limit.

Researchers demonstrated that attackers can bypass authentication entirely using simple payloads like AAAAAA'or'1'='1, which causes the SQL query to return successful authentication for any request. More sophisticated attacks leverage MySQL’s INTO OUTFILE statement to write arbitrary files to the filesystem.

The vulnerability becomes particularly dangerous due to FortiWeb’s configuration, where the MySQL process runs with root privileges rather than the typical restricted mysql user account.

This misconfiguration allows attackers to write files anywhere on the system with root permissions.

Researchers successfully escalated the SQL injection to remote code execution by exploiting Python’s site-packages mechanism. They demonstrated writing malicious .pth Files containing Python code that execute automatically when the system’s CGI scripts run Python processes.

The attack chain involves injecting payloads that store malicious Python code in the database, then using UNION SELECT statements with INTO OUTFILE to write the code to Python’s site-packages directory.

When legitimate Python CGI scripts execute, the malicious code runs automatically with system privileges.

Organizations using affected FortiWeb versions should immediately apply available patches. As interim mitigation, administrators should restrict access to Fabric Connector API endpoints and monitor for suspicious authentication attempts targeting /api/fabric/ paths.

The combination of unauthenticated access, root-level MySQL execution, and accessible code execution paths created a perfect storm for critical system compromise.

Fortinet has acknowledged the vulnerability and provided patches addressing the underlying SQL injection by implementing proper parameterized queries using prepared statements instead of string concatenation.

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