CVE-2025-69247 Overview
CVE-2025-69247 is a Heap-based Buffer Overflow vulnerability (CWE-122) in the free5GC go-upf component, which serves as the User Plane Function (UPF) implementation for 5G networks within the free5GC project. This vulnerability allows remote attackers to crash the UPF network element by sending a specially crafted PFCP (Packet Forwarding Control Protocol) Session Modification Request containing an invalid SDF Filter length field.
The heap buffer overflow results in a Denial of Service condition, causing complete service disruption for all connected User Equipment (UEs) and potentially triggering cascading failures that can affect the Session Management Function (SMF) and broader 5G network operations.
Critical Impact
Remote attackers can cause complete service disruption for all connected UEs in 5G deployments by exploiting this heap buffer overflow, with potential cascading failures affecting the SMF component.
Affected Products
- free5GC go-upf versions prior to 1.2.8
- All free5GC deployments utilizing the UPF component
Discovery Timeline
- 2026-02-23 - CVE-2025-69247 published to NVD
- 2026-02-25 - Last updated in NVD database
Technical Details for CVE-2025-69247
Vulnerability Analysis
This vulnerability exists in how the free5GC go-upf component processes PFCP Session Modification Requests. The PFCP protocol is used in 5G networks for communication between the control plane and user plane functions. When processing incoming PFCP messages, the UPF fails to properly validate the length field of SDF (Service Data Flow) Filter parameters.
The lack of proper bounds checking allows an attacker to specify an invalid length value that causes the application to read or write beyond the allocated heap buffer boundaries. This memory corruption ultimately leads to a crash of the UPF process, disrupting all user plane traffic processing for the affected 5G network segment.
Root Cause
The root cause is improper input validation (CWE-122: Heap-based Buffer Overflow) in the PFCP message parsing logic. Specifically, the code does not adequately validate the SDF Filter length field before using it to determine memory operations. When an attacker supplies a maliciously crafted length value, the application performs heap buffer operations that exceed the allocated memory region, leading to memory corruption and process termination.
Attack Vector
The attack can be executed remotely over the network without requiring authentication or user interaction. An attacker with network access to the PFCP interface of the UPF can exploit this vulnerability by:
- Establishing a connection to the UPF's PFCP endpoint
- Crafting a PFCP Session Modification Request message
- Including an SDF Filter Information Element with an invalid/malicious length field
- Sending the malformed request to trigger the heap buffer overflow
The vulnerability is exploited through malformed PFCP Session Modification Request messages. When the UPF attempts to process the SDF Filter with an invalid length field, it causes a heap buffer overflow condition. Attackers craft these messages by manipulating the length field in the SDF Filter IE (Information Element) to exceed expected boundaries. For detailed technical information, refer to the GitHub Security Advisory.
Detection Methods for CVE-2025-69247
Indicators of Compromise
- Unexpected UPF process crashes or restarts in free5GC deployments
- Malformed PFCP Session Modification Request messages in network traffic logs
- PFCP messages containing abnormally large or negative SDF Filter length values
- Increased error rates or connection failures for connected UE devices
Detection Strategies
- Monitor PFCP traffic for malformed Session Modification Requests with invalid SDF Filter length fields
- Implement network-level anomaly detection for unusual PFCP message patterns
- Deploy intrusion detection rules to identify packets with suspicious length field values in PFCP messages
- Set up crash monitoring and alerting for the go-upf process
Monitoring Recommendations
- Enable detailed logging for PFCP message processing in the UPF component
- Configure process health monitoring to detect and alert on UPF crashes
- Implement network traffic analysis on PFCP interfaces (typically UDP port 8805)
- Establish baseline metrics for normal PFCP traffic patterns to detect anomalies
How to Mitigate CVE-2025-69247
Immediate Actions Required
- Upgrade free5GC go-upf to version 1.2.8 or later immediately
- Review network segmentation to restrict access to PFCP interfaces
- Implement firewall rules to limit PFCP traffic to trusted SMF components only
- Enable enhanced logging to detect potential exploitation attempts
Patch Information
The vulnerability has been addressed in go-upf version 1.2.8. The fix implements proper validation of the SDF Filter length field before processing PFCP Session Modification Requests, preventing the heap buffer overflow condition.
Relevant resources for applying the fix:
Workarounds
- Restrict network access to PFCP interfaces using firewall rules, allowing only trusted SMF IP addresses
- Deploy a network-level filter or WAF to inspect and block malformed PFCP messages
- Consider deploying UPF redundancy to minimize service impact in case of exploitation
- Monitor for and automatically restart crashed UPF processes while working toward applying the patch
# Example: Restrict PFCP interface access using iptables
# Allow PFCP traffic only from trusted SMF 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.
