CVE-2025-69248 Overview
CVE-2025-69248 is a Buffer Overflow vulnerability in the free5GC AMF (Access and Mobility Management Function) service, an open-source implementation for 5th generation (5G) mobile core networks. This vulnerability affects versions up to and including 1.4.1 and allows remote unauthenticated attackers to crash the AMF service by sending a specially crafted NAS (Non-Access Stratum) Registration Request containing a malformed 5GS Mobile Identity. Successful exploitation results in complete denial of service for the 5G core network infrastructure.
Critical Impact
Remote unauthenticated attackers can cause complete denial of service for 5G core network deployments by crashing the AMF service with malformed NAS Registration Requests.
Affected Products
- free5GC AMF versions up to and including 1.4.1
- All free5GC deployments utilizing the AMF component
- free5GC NAS library (prior to patch in Pull Request #43)
Discovery Timeline
- 2026-02-23 - CVE-2025-69248 published to NVD
- 2026-02-25 - Last updated in NVD database
Technical Details for CVE-2025-69248
Vulnerability Analysis
This Buffer Overflow vulnerability (classified under CWE-129: Improper Validation of Array Index) exists in the free5GC AMF service's handling of NAS Registration Requests. The vulnerability stems from insufficient input validation when processing the 5GS Mobile Identity field within incoming NAS protocol messages. When an attacker submits a malformed 5GS Mobile Identity, the parsing logic fails to properly validate array boundaries, leading to a buffer overflow condition that crashes the AMF process.
The AMF service is a critical component of 5G network architecture, responsible for handling registration, connection, reachability, and mobility management for User Equipment (UE). A denial of service against this component effectively disrupts all 5G network operations for the affected deployment.
Root Cause
The root cause of CVE-2025-69248 is improper validation of array index operations (CWE-129) when parsing the 5GS Mobile Identity field in NAS Registration Requests. The AMF service's NAS message parser does not adequately verify the boundaries of input data before accessing array elements, allowing a crafted payload to trigger an out-of-bounds memory access. This results in a buffer overflow that terminates the AMF process unexpectedly.
Attack Vector
The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by sending specially crafted NAS Registration Request messages to the AMF service over the network. The attack does not require prior access to the 5G network or any credentials, making it particularly dangerous for exposed free5GC deployments.
The malformed 5GS Mobile Identity triggers the buffer overflow during NAS message parsing, causing the AMF service to crash. Since the AMF is central to 5G core network operations, this results in a complete denial of service condition affecting all connected devices and services.
Detection Methods for CVE-2025-69248
Indicators of Compromise
- Unexpected crashes or restarts of the free5GC AMF service
- Core dump files generated by the AMF process indicating segmentation faults
- Anomalous NAS Registration Request patterns in network traffic logs
- Multiple failed or incomplete UE registration attempts coinciding with AMF service disruptions
Detection Strategies
- Monitor AMF process stability and implement alerting for unexpected service terminations
- Deploy network traffic analysis to identify malformed NAS Registration Requests targeting the AMF
- Implement deep packet inspection for 5G NAS protocol anomalies, specifically in the 5GS Mobile Identity field
- Review AMF service logs for parsing errors or exceptions related to mobile identity processing
Monitoring Recommendations
- Configure process monitoring and automatic restart capabilities for the AMF service
- Establish baseline metrics for NAS Registration Request volumes and alert on significant deviations
- Enable verbose logging for the AMF component to capture detailed error information during parsing operations
- Implement network segmentation to limit exposure of the AMF service to untrusted networks
How to Mitigate CVE-2025-69248
Immediate Actions Required
- Apply the official patch from GitHub NAS Pull Request #43 immediately
- Review the security advisory at GHSA-h6xc-8vvf-jcjp for detailed guidance
- Restrict network access to the AMF service to trusted sources only
- Implement rate limiting on incoming NAS Registration Requests as a temporary measure
Patch Information
The vulnerability has been addressed in the free5GC NAS library. The fix is available through Pull Request #43 in the free5gc/nas repository. The specific commit addressing this vulnerability is 0329a7ac3f314f210366c1b3c33dc29eded4ac5f, which can be reviewed at the GitHub NAS Commit.
Organizations running free5GC should update their NAS library dependency to a version that includes this patch. For tracking purposes, the issue is documented in the free5GC Issue Tracker.
Workarounds
- No direct workaround is available at the application level; applying the official patch is strongly recommended
- Implement network-level controls to restrict access to the AMF service from untrusted sources
- Deploy a reverse proxy or firewall with deep packet inspection to filter malformed NAS messages
- Consider placing the AMF service behind additional network security controls until patching is complete
# Update free5GC NAS library to patched version
cd /path/to/free5gc
git submodule update --remote NFs/nas
# Alternatively, apply specific commit
cd NFs/nas
git fetch origin
git checkout 0329a7ac3f314f210366c1b3c33dc29eded4ac5f
# Rebuild the AMF service
cd ../..
make amf
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
