CVE-2025-20315 Overview
A vulnerability in the Network-Based Application Recognition (NBAR) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to improper handling of malformed Control and Provisioning of Wireless Access Points (CAPWAP) packets. An attacker could exploit this vulnerability by sending malformed CAPWAP packets through an affected device, causing unexpected device reloads and service disruption.
Critical Impact
Unauthenticated remote attackers can cause network infrastructure devices running Cisco IOS XE to reload unexpectedly, disrupting network operations and potentially affecting downstream services dependent on the affected device.
Affected Products
- Cisco IOS XE Software with NBAR feature enabled
- Devices processing CAPWAP traffic
- Wireless LAN controllers and access point infrastructure
Discovery Timeline
- 2025-09-24 - CVE-2025-20315 published to NVD
- 2025-09-26 - Last updated in NVD database
Technical Details for CVE-2025-20315
Vulnerability Analysis
This vulnerability resides in the Network-Based Application Recognition (NBAR) feature of Cisco IOS XE Software. NBAR is a classification engine that recognizes and classifies applications and protocols using static assignment or deep packet inspection techniques. The vulnerability specifically affects how the system processes Control and Provisioning of Wireless Access Points (CAPWAP) protocol packets.
The weakness is classified as CWE-805 (Buffer Access with Incorrect Length Value), indicating that the software accesses a buffer using an incorrect length value, which can lead to memory corruption or unexpected behavior. In this case, the improper handling of malformed CAPWAP packets triggers a condition that causes the affected device to reload.
Root Cause
The root cause of this vulnerability is improper validation and handling of CAPWAP packet structures within the NBAR processing engine. When malformed CAPWAP packets are received and processed by an affected device, the software fails to properly validate packet boundaries or length fields, leading to buffer access with incorrect length values. This memory handling error results in a system crash and subsequent device reload.
Attack Vector
This vulnerability can be exploited remotely over the network by an unauthenticated attacker. The attack requires no privileges or user interaction, making it particularly dangerous in production environments. An attacker would craft and send malformed CAPWAP packets through or to an affected device. The attack can be initiated from any network position that allows CAPWAP traffic to reach the vulnerable device.
The CAPWAP protocol typically operates on UDP ports 5246 (control) and 5247 (data), which may be exposed in wireless network infrastructure environments. The scope of impact extends beyond the vulnerable component itself, as a network device reload can affect all services and traffic flowing through that device.
Detection Methods for CVE-2025-20315
Indicators of Compromise
- Unexpected device reloads on Cisco IOS XE devices with NBAR enabled
- Crash logs indicating NBAR or CAPWAP-related exceptions
- Anomalous CAPWAP traffic patterns with malformed packet structures
- Repeated system reboots correlating with CAPWAP traffic spikes
Detection Strategies
- Monitor syslog for device reload events and correlate with CAPWAP traffic
- Implement deep packet inspection for malformed CAPWAP packets on UDP ports 5246 and 5247
- Deploy network-based intrusion detection rules to identify anomalous CAPWAP packet structures
- Enable crash dump collection on Cisco IOS XE devices for forensic analysis
Monitoring Recommendations
- Configure SNMP traps for device reload events on all Cisco IOS XE infrastructure
- Establish baseline CAPWAP traffic patterns and alert on significant deviations
- Implement centralized logging for all network infrastructure devices
- Monitor device uptime metrics and create alerts for unexpected reloads
How to Mitigate CVE-2025-20315
Immediate Actions Required
- Review the Cisco Security Advisory for specific affected versions and patches
- Identify all Cisco IOS XE devices with NBAR feature enabled in your environment
- Apply vendor-provided patches as soon as they become available
- Consider disabling NBAR on devices where it is not required for business operations
Patch Information
Cisco has released a security advisory addressing this vulnerability. Administrators should consult the Cisco Security Advisory for specific details on affected software versions and available software updates. Organizations should prioritize patching network infrastructure devices, especially those exposed to untrusted network segments.
Workarounds
- Implement access control lists (ACLs) to restrict CAPWAP traffic to trusted sources only
- Disable NBAR feature if not required for operational needs
- Deploy network segmentation to limit exposure of vulnerable devices to untrusted traffic
- Configure rate limiting on CAPWAP protocol traffic to reduce attack impact
# Example ACL configuration to restrict CAPWAP traffic (consult Cisco documentation for your specific platform)
# Restrict CAPWAP control traffic (UDP 5246) to trusted wireless infrastructure
access-list 100 permit udp host <trusted_controller_ip> any eq 5246
access-list 100 permit udp host <trusted_ap_subnet> any eq 5246
access-list 100 deny udp any any eq 5246
access-list 100 permit ip any any
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
