CVE-2025-69232 Overview
CVE-2025-69232 is an Improper Input Validation and Protocol Compliance vulnerability affecting free5GC, an open-source project for 5th generation (5G) mobile core networks. The vulnerability exists in free5GC go-upf versions up to and including 1.2.6, corresponding to free5gc smf up to and including 1.4.0. Remote attackers can exploit this flaw to disrupt core network functionality by sending a malformed PFCP Association Setup Request, causing the User Plane Function (UPF) to enter an inconsistent state that triggers SMF reconnection loops and service degradation.
Critical Impact
Remote attackers can cause Denial of Service conditions in 5G core network deployments by sending malformed PFCP Association Setup Requests, disrupting legitimate network operations and causing service degradation.
Affected Products
- free5gc go-upf versions up to and including 1.2.6
- free5gc smf versions up to and including 1.4.0
- All free5GC deployments using UPF and SMF components
Discovery Timeline
- 2026-02-23 - CVE-2025-69232 published to NVD
- 2026-02-25 - Last updated in NVD database
Technical Details for CVE-2025-69232
Vulnerability Analysis
This vulnerability stems from improper input validation in the PFCP (Packet Forwarding Control Protocol) message handling within free5GC's User Plane Function component. PFCP is a critical protocol in 5G architecture used for communication between the Session Management Function (SMF) and the UPF. When the UPF receives a malformed PFCP Association Setup Request, it fails to properly validate the request against protocol specifications and incorrectly accepts the malformed message. This causes the UPF to enter an inconsistent internal state.
The impact is significant for 5G network operations: once the UPF enters this inconsistent state, subsequent legitimate PFCP requests from the SMF trigger reconnection loops. This creates a cascading failure where the SMF repeatedly attempts to re-establish associations, consuming resources and degrading overall network service quality.
Root Cause
The root cause is classified under CWE-20 (Improper Input Validation). The go-upf component does not adequately validate incoming PFCP Association Setup Request messages against the expected protocol format and mandatory fields. This lack of validation allows malformed packets to be processed as valid, leading to state corruption within the UPF's association management logic.
Attack Vector
The attack is network-accessible and requires no authentication or user interaction. An attacker with network access to the PFCP interface can craft and send a malformed PFCP Association Setup Request to the UPF. The malformed request bypasses validation checks and is incorrectly accepted by the UPF.
The attack flow proceeds as follows:
- Attacker identifies a free5GC deployment with an accessible UPF PFCP interface
- Attacker crafts a malformed PFCP Association Setup Request that violates protocol specifications
- The UPF accepts the malformed request due to insufficient validation
- The UPF enters an inconsistent state affecting association management
- Subsequent legitimate SMF requests trigger reconnection loops
- Service degradation occurs across the 5G core network
For technical details on the vulnerability mechanism, refer to the GitHub Security Advisory GHSA-8m42-qw58-8362.
Detection Methods for CVE-2025-69232
Indicators of Compromise
- Unusual patterns of PFCP Association Setup Request messages from unexpected sources
- Repeated SMF-to-UPF reconnection attempts visible in network logs
- Service degradation symptoms including increased latency or connection failures in 5G core operations
- UPF log entries indicating association state inconsistencies or unexpected state transitions
Detection Strategies
- Monitor PFCP traffic on port 8805 (default PFCP port) for malformed or anomalous Association Setup Requests
- Implement network intrusion detection rules to identify PFCP messages that deviate from expected protocol structure
- Configure alerting on SMF reconnection loop patterns that exceed normal operational thresholds
- Deploy deep packet inspection for PFCP traffic to validate message structure compliance
Monitoring Recommendations
- Enable detailed logging on both UPF and SMF components to capture PFCP message exchanges and state transitions
- Implement baseline monitoring for normal PFCP association establishment patterns to detect anomalies
- Set up alerts for UPF service degradation indicators such as increased error rates or processing delays
- Monitor network traffic patterns for unusual volumes of PFCP messages from single sources
How to Mitigate CVE-2025-69232
Immediate Actions Required
- Restrict network access to the PFCP interface to only authorized SMF components using firewall rules or network segmentation
- Implement network-level filtering to drop PFCP packets from untrusted sources
- Monitor free5GC project releases for the official security patch and plan for immediate deployment
- Consider deploying temporary network monitoring to detect exploitation attempts
Patch Information
As of the publication date, a fix is in development but not yet available. Organizations should monitor the free5GC GitHub repository for patch release announcements. Applying the official patch once released is the recommended remediation approach.
For more information, refer to:
Workarounds
- No direct workaround is available at the application level per the vendor advisory
- Implement strict network segmentation to isolate the PFCP interface from untrusted networks
- Deploy firewall rules to allow PFCP traffic only from known, legitimate SMF IP addresses
- Consider placing a protocol-aware proxy or filtering appliance in front of the UPF to validate PFCP message structure
# Example: Restrict PFCP interface access using iptables
# Allow PFCP (port 8805) only from trusted SMF IP addresses
iptables -A INPUT -p udp --dport 8805 -s <TRUSTED_SMF_IP> -j ACCEPT
iptables -A INPUT -p udp --dport 8805 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
