CVE-2024-20259 Overview
A vulnerability exists in the DHCP snooping feature of Cisco IOS XE Software that could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is caused by improper handling of crafted IPv4 DHCP request packets when endpoint analytics are enabled.
An attacker could exploit this vulnerability by sending a crafted DHCP request through an affected device. A successful exploit could force the device to reload, disrupting network operations and causing service outages. Notably, the attack vector is classified as network-based because a DHCP relay anywhere on the network could allow exploits from networks other than the adjacent one, significantly expanding the potential attack surface.
Critical Impact
Unauthenticated remote attackers can cause network infrastructure devices to reload, resulting in denial of service conditions that disrupt critical network services across enterprise environments.
Affected Products
- Cisco IOS XE Software (versions 17.1.1 through 17.12.1w)
- Cisco Catalyst 9000 Series Switches (9200, 9300, 9400, 9600 families)
- Cisco Catalyst 9800 Series Wireless Controllers
- Cisco Catalyst 9100 Series Access Points
Discovery Timeline
- March 27, 2024 - CVE-2024-20259 published to NVD
- April 30, 2025 - Last updated in NVD database
Technical Details for CVE-2024-20259
Vulnerability Analysis
This vulnerability stems from improper memory handling within the DHCP snooping feature when processing IPv4 DHCP request packets. The weakness is classified under CWE-122 (Heap-based Buffer Overflow) and CWE-787 (Out-of-bounds Write), indicating that the vulnerability involves writing data beyond the boundaries of allocated memory buffers.
When endpoint analytics are enabled on affected devices, the DHCP snooping component fails to properly validate and handle certain malformed DHCP request packets. This improper handling can trigger a memory corruption condition that causes the device to crash and reload. The vulnerability is particularly concerning because it requires no authentication to exploit and can be triggered remotely across the network.
The scope of this vulnerability is changed, meaning successful exploitation can impact resources beyond the vulnerable component itself—in this case, the entire network infrastructure that depends on the affected device for connectivity.
Root Cause
The root cause of this vulnerability is a heap-based buffer overflow (CWE-122) combined with out-of-bounds write conditions (CWE-787) in the DHCP snooping implementation. When the DHCP snooping feature processes specially crafted IPv4 DHCP request packets while endpoint analytics are active, the code fails to properly validate packet contents before writing to memory buffers. This allows an attacker to cause memory corruption that triggers an unrecoverable error, forcing the device to reload.
Attack Vector
The vulnerability can be exploited remotely over the network without requiring authentication or user interaction. An attacker needs to send a specially crafted IPv4 DHCP request packet to or through an affected device. The attack can be executed from any network segment that has DHCP relay capabilities, not just from the local network segment where the vulnerable device resides.
The exploitation flow is as follows:
- The attacker crafts a malicious IPv4 DHCP request packet with specific payload characteristics
- The packet is sent to or relayed through the affected Cisco IOS XE device
- The DHCP snooping feature attempts to process the packet with endpoint analytics enabled
- Improper handling triggers a heap buffer overflow condition
- The memory corruption causes the device to crash and reload
- Network services dependent on the device become unavailable during the reload
Detection Methods for CVE-2024-20259
Indicators of Compromise
- Unexpected device reloads or crashes on Cisco Catalyst switches and wireless controllers
- Crash dump files indicating memory corruption in DHCP-related processes
- Unusual DHCP traffic patterns with malformed request packets
- System logs showing abnormal terminations related to DHCP snooping processes
Detection Strategies
- Monitor network devices for unexpected reloads using SNMP traps and syslog messages
- Implement network traffic analysis to detect anomalous DHCP packet patterns
- Configure logging to capture DHCP snooping events and correlation with device stability issues
- Use network monitoring tools to track device uptime and identify patterns of instability
Monitoring Recommendations
- Enable comprehensive logging on all affected Cisco IOS XE devices
- Configure SNMP monitoring to alert on device reload events
- Implement NetFlow or equivalent traffic analysis to monitor DHCP traffic patterns
- Review crash dump files on affected devices for indicators of exploitation attempts
How to Mitigate CVE-2024-20259
Immediate Actions Required
- Review the Cisco Security Advisory for specific guidance and fixed software versions
- Identify all Cisco IOS XE devices running affected software versions in your environment
- Prioritize patching for devices in critical network paths or exposed to untrusted networks
- Consider temporarily disabling endpoint analytics on DHCP snooping if patching is not immediately possible
Patch Information
Cisco has released security patches to address this vulnerability. Organizations should consult the Cisco Security Advisory for details on fixed software versions and upgrade paths specific to their deployment. The advisory includes information on which IOS XE software trains contain the fix and provides guidance for selecting the appropriate upgraded version.
Workarounds
- Disable endpoint analytics on DHCP snooping if the feature is not required for operations
- Implement access control lists (ACLs) to restrict DHCP traffic from untrusted sources
- Segment the network to limit the reach of potential DHCP-based attacks
- Enable DHCP rate limiting on interfaces to reduce the impact of malformed packet floods
# Example: Check current DHCP snooping and endpoint analytics configuration
show ip dhcp snooping
show analytics configuration
# Example: Disable endpoint analytics (consult Cisco documentation for your specific deployment)
# This may serve as a temporary workaround until patching is complete
configure terminal
no analytics endpoint
end
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
