Overview

The vulnerability CVE-2025-56394 is a severe security flaw present in Free5gc 4.0.1, an open-source 5G core network project. This vulnerability can lead to a buffer overflow situation due to incorrect validation of the 5GS mobile identity by the AMF. This flaw could potentially compromise the entire system or leak sensitive data. Companies using Free5gc 4.0.1 are at risk and need to take immediate action to prevent malicious exploitation.

Vulnerability Summary

CVE ID: CVE-2025-56394
Severity: High – CVSS 7.5
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: System Compromise and Data Leakage

Affected Products

Product | Affected Versions

Free5gc | 4.0.1

How the Exploit Works

The exploit takes advantage of a flaw in the AMF’s validation of the 5GS mobile identity. By crafting a malicious 5GS identity, an attacker can trigger a buffer overflow in the AMF, causing an overflow of slice references. This overflow can lead to unexpected behavior, including potential system crashes or the execution of arbitrary code. The attacker could gain unauthorized access to the system and potentially exfiltrate sensitive data.

Conceptual Example Code

Here is a conceptual example of how an attacker might exploit this vulnerability. The attacker sends a specially crafted 5GS mobile identity that causes a buffer overflow.

POST /amf/ueContexts HTTP/1.1
Host: target.example.com
Content-Type: application/json
{
"5gsIdentity": "malicious_5gs_identity_string_that_causes_buffer_overflow"
}

Mitigation Guidance

Users of Free5gc 4.0.1 are advised to apply the vendor’s patch to fix this vulnerability. As a temporary mitigation, a web application firewall (WAF) or intrusion detection system (IDS) can be used to intercept and inspect traffic for malicious patterns related to this exploit. However, this is not a full-proof solution and may only serve as a stopgap measure until the patch can be deployed.