Published on: 2025-11-18
Overview
CVE-2025-48839 describes an Out-of-Bounds Write vulnerability (CWE-787) affecting multiple versions of FortiADC. This flaw can allow an authenticated attacker to potentially execute arbitrary code by sending specially crafted HTTP requests to a vulnerable FortiADC instance. Organizations using affected versions are strongly advised to apply the appropriate patches as soon as possible.
Technical Details
The vulnerability lies in how FortiADC processes incoming HTTP requests. A malformed request can trigger the software to write data beyond the allocated buffer, leading to a memory corruption. This out-of-bounds write can overwrite critical program data or even executable code, potentially allowing an attacker to gain control of the system. The exact location and mechanism of the vulnerability likely varies across the affected versions, but the underlying principle remains the same: insufficient input validation allows attackers to overwrite memory.
Exploitation requires an authenticated attacker, meaning they need to have valid credentials to access the FortiADC management interface or a component handling HTTP requests. The nature of the specially crafted HTTP requests is not publicly available at this time, but further analysis and reverse engineering efforts may reveal specific payload structures. The complexity of crafting such a request is currently unknown, but its authentication requirement limits the scope of exploitation.
CVSS Analysis
The vulnerability has been assigned a CVSS score of 6.6 (MEDIUM). This score reflects the following factors:
- Attack Vector: Network
- Attack Complexity: High (due to the need to craft a specific HTTP request and potentially bypass input validation)
- Privileges Required: High (Authentication required)
- User Interaction: None
- Scope: Changed
- Confidentiality Impact: High
- Integrity Impact: High
- Availability Impact: High
While the score is Medium, the potential for arbitrary code execution makes this a serious vulnerability that requires prompt attention.
Possible Impact
Successful exploitation of CVE-2025-48839 could lead to a number of severe consequences:
- Arbitrary Code Execution: The attacker can execute commands on the affected FortiADC appliance, potentially gaining complete control of the device.
- Data Breach: Compromised FortiADC appliances could be used to intercept and exfiltrate sensitive data passing through the device.
- Denial of Service (DoS): Exploitation could crash the FortiADC appliance, disrupting network services.
- Lateral Movement: Attackers could use the compromised FortiADC appliance as a pivot point to attack other systems on the network.
Mitigation and Patch Steps
The primary mitigation strategy is to update FortiADC to a patched version. Fortinet has likely released updates to address this vulnerability. Please refer to the Fortinet advisory for the specific versions that contain the fix.
- Identify Affected Systems: Determine which FortiADC appliances in your environment are running the vulnerable versions (8.0.0, 7.6.0 through 7.6.2, 7.4.0 through 7.4.7, 7.2 all versions, 7.1 all versions, 7.0 all versions, 6.2 all versions).
- Apply Patches: Download and install the latest FortiADC firmware from the Fortinet support portal. Follow Fortinet’s instructions carefully to ensure a successful update.
- Verify the Update: After applying the patch, verify that the FortiADC appliance is running the patched version.
- Monitor for Suspicious Activity: Even after patching, continue to monitor network traffic and system logs for any signs of suspicious activity.
