CVE-2025-25250: Fortinet FortiOS Info Disclosure Flaw

CVE-2025-25250 Overview

CVE-2025-25250 is an Exposure of Sensitive Information to an Unauthorized Actor vulnerability (CWE-200) affecting Fortinet FortiOS and FortiSASE products. The vulnerability exists in the SSL-VPN web-mode feature, where an authenticated user can access full SSL-VPN settings through a crafted URL. This information disclosure flaw allows low-privileged authenticated users to retrieve sensitive configuration details that should be restricted to administrators.

Critical Impact

Authenticated attackers can access full SSL-VPN configuration settings, potentially exposing sensitive network architecture details, authentication policies, and security configurations that could be leveraged for further attacks.

Affected Products

• Fortinet FortiOS version 7.6.0
• Fortinet FortiOS version 7.4.7 and below
• Fortinet FortiOS versions 7.2 all versions
• Fortinet FortiOS versions 7.0 all versions
• Fortinet FortiOS versions 6.4 all versions
• Fortinet FortiSASE version 25.1.75

Discovery Timeline

• 2025-06-10 - CVE-2025-25250 published to NVD
• 2025-07-22 - Last updated in NVD database

Technical Details for CVE-2025-25250

Vulnerability Analysis

This vulnerability represents a significant information exposure risk within Fortinet's SSL-VPN web-mode implementation. The flaw allows authenticated users—even those with minimal privileges—to craft specific URLs that bypass normal access controls and retrieve comprehensive SSL-VPN configuration data.

The exposed information could include VPN endpoint configurations, authentication realm settings, portal customizations, and potentially sensitive network topology details. While the vulnerability requires authentication, it violates the principle of least privilege by allowing any authenticated user to access administrator-level configuration visibility.

The network-based attack vector with low complexity makes this vulnerability particularly concerning in environments where multiple users have SSL-VPN web-mode access. An attacker who has compromised any user account could exploit this vulnerability to perform reconnaissance and gather intelligence for more sophisticated attacks.

Root Cause

The root cause of CVE-2025-25250 lies in improper access control validation within the FortiOS SSL-VPN web-mode request handling. The affected component fails to properly verify that the requesting user has appropriate authorization to access full SSL-VPN settings before returning the configuration data. When processing specially crafted URLs, the application does not enforce role-based access controls, resulting in sensitive configuration information being exposed to any authenticated user regardless of their privilege level.

Attack Vector

The attack is conducted over the network against the SSL-VPN web-mode interface. An attacker must first obtain valid authentication credentials for any user account with SSL-VPN access. Once authenticated, the attacker can manipulate URL parameters or paths to request SSL-VPN configuration endpoints that would normally be restricted. The low attack complexity indicates that no special conditions or additional preparations are required beyond crafting the malicious URL request.

The exploitation scenario involves:

1. Attacker authenticates to the SSL-VPN web-mode portal with any valid user credentials
2. Attacker crafts a specific URL targeting the SSL-VPN settings endpoint
3. The vulnerable FortiOS instance returns full SSL-VPN configuration without proper authorization checks
4. Attacker obtains sensitive configuration details for further reconnaissance or attack planning

Detection Methods for CVE-2025-25250

Indicators of Compromise

• Unusual access patterns to SSL-VPN administrative configuration endpoints from non-administrative user sessions
• Anomalous URL requests containing configuration retrieval parameters from standard VPN users
• Increased volume of configuration-related requests from single authenticated sessions
• Log entries showing access to restricted SSL-VPN settings endpoints by low-privileged accounts

Detection Strategies

• Monitor FortiOS logs for authentication events followed by configuration access attempts from the same session
• Implement URL request monitoring for SSL-VPN web-mode to detect crafted URL patterns targeting settings endpoints
• Configure alerting for any non-administrative user accessing configuration-related API endpoints
• Deploy network traffic analysis to identify unusual request patterns against FortiGate SSL-VPN interfaces

Monitoring Recommendations

• Enable verbose logging for SSL-VPN web-mode access and review logs for suspicious activity patterns
• Implement SIEM correlation rules to detect configuration access attempts from non-administrative users
• Monitor for reconnaissance activity following any suspected exploitation attempts
• Review user access patterns to identify potential credential compromise used in exploitation chains

How to Mitigate CVE-2025-25250

Immediate Actions Required

• Apply the security patches provided by Fortinet as outlined in Fortinet Security Advisory FG-IR-24-257
• Review FortiOS logs for any evidence of past exploitation attempts
• Audit user accounts with SSL-VPN web-mode access and verify their privilege levels are appropriate
• Consider restricting SSL-VPN web-mode access to essential users only until patching is complete

Patch Information

Fortinet has released security updates to address this vulnerability. Organizations should upgrade to patched versions as specified in the Fortinet Security Advisory FG-IR-24-257. The advisory provides specific version guidance for FortiOS and FortiSASE deployments.

For FortiOS deployments:

• Version 7.6.x: Upgrade to version higher than 7.6.0
• Version 7.4.x: Upgrade to version higher than 7.4.7
• Versions 7.2, 7.0, and 6.4: Consult the security advisory for migration paths to supported versions

Workarounds

• Disable SSL-VPN web-mode functionality if not operationally required, using tunnel-mode only
• Implement strict network segmentation to limit access to SSL-VPN management interfaces
• Enforce multi-factor authentication for all SSL-VPN users to reduce the risk of credential compromise
• Apply IP-based access restrictions to limit SSL-VPN access to known, trusted networks

# Configuration example - Disable SSL-VPN web-mode if not required
# Access FortiGate CLI and configure tunnel-mode only
config vpn ssl settings
    set tunnel-mode-only enable
end

# Alternatively, restrict SSL-VPN access to specific source addresses
config vpn ssl settings
    set source-address "Trusted_IP_Group"
end