CVE-2026-2525 Overview
A denial of service vulnerability has been identified in Free5GC, an open-source implementation of 5G core network components. The vulnerability exists in the PFCP (Packet Forwarding Control Protocol) UDP Endpoint component within Free5GC versions up to and including 4.1.0. An attacker can remotely exploit this flaw to cause service disruption, potentially affecting the availability of 5G core network functions.
Critical Impact
Remote attackers can disrupt 5G core network operations by targeting the PFCP UDP Endpoint, causing denial of service conditions without requiring authentication.
Affected Products
- Free5GC versions up to 4.1.0
- Free5GC PFCP UDP Endpoint component
- 5G core network deployments utilizing Free5GC
Discovery Timeline
- February 16, 2026 - CVE-2026-2525 published to NVD
- February 19, 2026 - Last updated in NVD database
Technical Details for CVE-2026-2525
Vulnerability Analysis
This vulnerability affects the PFCP UDP Endpoint functionality within Free5GC. PFCP is a critical protocol used in 5G networks for communication between the Session Management Function (SMF) and User Plane Function (UPF). The vulnerability stems from improper resource release (CWE-404), where the affected component fails to properly handle certain inputs, leading to resource exhaustion and subsequent denial of service conditions.
The network-based attack vector means that exploitation can occur remotely without requiring local access to the target system. Additionally, the attack requires no privileges or user interaction, making it accessible to unauthenticated attackers who can reach the PFCP endpoint over the network.
Root Cause
The root cause is classified as CWE-404: Improper Resource Shutdown or Release. The PFCP UDP Endpoint does not properly release allocated resources under certain conditions, which can be triggered by specially crafted network traffic. This improper cleanup leads to resource depletion over time or through sustained attack, eventually causing the service to become unavailable.
Attack Vector
The attack is network-based and can be launched remotely against exposed PFCP UDP endpoints. An attacker sends malicious or malformed PFCP messages to the target endpoint, triggering the improper resource handling behavior. Since PFCP typically operates on UDP port 8805, attackers can target this service if it is accessible from their network position.
The vulnerability mechanism involves sending crafted packets to the PFCP UDP endpoint that cause resource allocation without proper subsequent release. Over repeated exploitation, this leads to resource exhaustion and denial of service. Technical details are available in the Free5GC GitHub Issue #796.
Detection Methods for CVE-2026-2525
Indicators of Compromise
- Unusual volume of UDP traffic targeting port 8805 (PFCP default port)
- Resource exhaustion symptoms on systems running Free5GC components
- Unexpected crashes or restarts of Free5GC services, particularly UPF or SMF components
- Memory or socket resource depletion alerts on affected systems
Detection Strategies
- Monitor network traffic for abnormal patterns targeting PFCP UDP endpoints (port 8805)
- Implement rate limiting and anomaly detection for PFCP protocol messages
- Configure system monitoring to alert on resource utilization spikes in Free5GC processes
- Deploy intrusion detection rules to identify malformed or suspicious PFCP packets
Monitoring Recommendations
- Enable detailed logging for Free5GC PFCP-related components
- Set up resource utilization thresholds and alerts for memory, CPU, and socket usage
- Monitor for repeated connection attempts or message floods to PFCP endpoints
- Review system logs regularly for signs of service degradation or unexpected behavior
How to Mitigate CVE-2026-2525
Immediate Actions Required
- Restrict network access to PFCP UDP endpoints using firewall rules, allowing only trusted sources
- Implement rate limiting on UDP traffic to port 8805 to reduce exploitation risk
- Monitor Free5GC deployments for signs of ongoing attacks or service degradation
- Review and update Free5GC to the latest available version once a patch is released
Patch Information
No official patch has been confirmed at the time of this publication. Users should monitor the Free5GC GitHub repository and the associated issue tracker for updates on available fixes. It is recommended to subscribe to security notifications from the Free5GC project for timely awareness of patches.
Workarounds
- Implement strict network segmentation to isolate PFCP endpoints from untrusted networks
- Deploy a firewall or access control list (ACL) to limit access to UDP port 8805 to authorized control plane components only
- Consider deploying an intrusion prevention system (IPS) with rules to detect and block malicious PFCP traffic
- Implement connection rate limiting and traffic shaping for PFCP communications
# Example: Restrict PFCP UDP endpoint access using iptables
# Allow only trusted SMF/UPF source IPs to access PFCP port
iptables -A INPUT -p udp --dport 8805 -s <TRUSTED_SMF_IP> -j ACCEPT
iptables -A INPUT -p udp --dport 8805 -s <TRUSTED_UPF_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.
