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CVE-2025-54820 is a high-severity stack-based buffer overflow vulnerability located in the `fgtupdates` service of Fortinet FortiManager . This service is responsible for handling updates to managed FortiGate devices . The flaw allows a remote, unauthenticated attacker to execute arbitrary code or unauthorized commands by sending specially crafted requests to the vulnerable service . The vulnerability exists due to improper handling of data, which can overflow a buffer on the stack . To achieve code execution, an attacker must successfully bypass the system’s built-in stack protection mechanisms, which increases the complexity of the attack . If exploited, an attacker can gain control of the FortiManager, which serves as the central management point for potentially hundreds of Fortinet devices . This foothold can then be used for lateral movement, deploying ransomware, exfiltrating sensitive configuration data, or causing widespread network disruption across the managed infrastructure . The issue was fixed in later versions, and a temporary workaround involves disabling the `fgtupdates` service via the CLI .
dailycve form:
Platform: FortiManager
Version: 7.4.0-7.4.2, 7.2.0-7.2.10, 6.4 all
Vulnerability : Stack Buffer Overflow
Severity: High (7.0 CVSS)
date: 03/10/2026
Prediction: Patch within 30 days
What Undercode Say:
Analytics:
- The vulnerability is present in on-premise versions of FortiManager, while FortiManager Cloud is unaffected .
- It was responsibly disclosed by researcher catalpa from Dbappsecurity Co., Ltd. .
- The attack vector is remote and requires no authentication, making it highly dangerous for exposed systems .
- Exploitation requires the `fgtupdates` service to be enabled on an accessible interface .
- A successful attack could lead to a full compromise of the FortiManager and all managed devices .
Exploit:
The core of the exploit involves sending a payload that exceeds the buffer size in the `fgtupdates` service. While a public proof-of-concept (PoC) is not detailed in the provided text, the attack would generally involve the following steps and concepts:
1. Reconnaissance: An attacker identifies a FortiManager instance with the `fgtupdates` service exposed.
2. Crafting the Payload: The attacker crafts a malicious network request. This request contains more data than the intended buffer can hold. This extra data is designed to:
– Overwrite the return address on the stack.
– Include shellcode (malicious machine code).
3. Bypassing Protections: The attacker must craft the payload to circumvent stack canaries or ASLR, as mentioned in the description .
4. Code Execution: Once the return address is successfully overwritten to point to the attacker’s shellcode, the shellcode executes with the privileges of the `fgtupdates` service.
A simplified, illustrative example (not the actual exploit) of a vulnerable C function concept:
include <string.h>
include <stdio.h>
void vulnerable_service(char user_input) {
char buffer[bash];
// No bounds checking! If user_input is >128 bytes, buffer overflows.
strcpy(buffer, user_input);
printf("Processing: %s\n", buffer);
}
int main(int argc, char argv[]) {
if (argc > 1) {
vulnerable_service(argv[bash]);
}
return 0;
}
Protection from this CVE:
1. Immediate Patching: Upgrade to the patched versions:
- Upgrade from 7.4.x to 7.4.3 or later .
- Upgrade from 7.2.x to 7.2.11 or later .
- Migrate from 6.4.x to a supported fixed release .
- Temporary Workaround: If patching is not immediately possible, disable the `fgtupdates` service via the CLI . Use the following commands:
config system interface edit <portID> set serviceaccess <list allowed services without "fgtupdates"> end
- Network Segmentation: Ensure FortiManager management interfaces are not exposed to the public internet and are only accessible from trusted internal networks .
Impact:
- Technical Impact: Unauthenticated remote code execution (RCE) on the FortiManager appliance .
- Business Impact: Complete compromise of the network management hub, leading to potential data breaches, ransomware deployment, and loss of control over all downstream FortiGate firewalls and security devices .
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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