CVE-2024-20436 in IOS XE
Summary
by MITRE • 09/25/2024
A vulnerability in the HTTP Server feature of Cisco IOS XE Software when the Telephony Service feature is enabled could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.
This vulnerability is due to a null pointer dereference when accessing specific URLs. An attacker could exploit this vulnerability by sending crafted HTTP traffic to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, causing a DoS condition on the affected device.
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Analysis
by VulDB Data Team • 09/27/2024
This vulnerability resides within the HTTP server implementation of Cisco IOS XE software and represents a critical denial of service weakness that can be exploited remotely without authentication. The flaw specifically manifests when the Telephony Service feature is active, creating a dangerous condition where legitimate network operations can be disrupted through carefully crafted HTTP requests. The vulnerability stems from improper handling of HTTP requests that target specific URLs within the telephony service interface, leading to a null pointer dereference error that ultimately triggers device system instability.
The technical root cause of CVE-2024-20436 aligns with CWE-476, which describes null pointer dereference conditions that occur when a program attempts to access memory through a null pointer reference. This particular weakness exists in the HTTP server component's request processing logic where it fails to validate or properly handle certain URL patterns that are associated with telephony service functionality. When an attacker crafts specific HTTP requests containing malformed or unexpected URL parameters, the system attempts to dereference a null pointer within the telephony service module, causing the device to crash and subsequently reload.
The operational impact of this vulnerability extends beyond simple service disruption as it can affect critical network infrastructure components that rely on telephony services for voice communication and integrated network management functions. Organizations utilizing Cisco IOS XE devices with telephony service enabled face potential business disruption when this vulnerability is exploited, as the device reload process can interrupt ongoing communications and require manual intervention for recovery. The remote nature of the attack means that adversaries can target these devices from outside the network perimeter, making the vulnerability particularly dangerous for organizations with exposed network services.
Mitigation strategies for this vulnerability should prioritize immediate patch management through official Cisco security advisories and firmware updates that address the null pointer dereference condition in the HTTP server component. Network segmentation and access control measures can help limit exposure by restricting direct HTTP access to affected devices, while monitoring systems should be implemented to detect anomalous HTTP traffic patterns that may indicate exploitation attempts. Organizations should also consider disabling unnecessary telephony service features when not required and implement proper network access controls to limit potential attack vectors. The vulnerability demonstrates the importance of thorough input validation in network service implementations and highlights the need for robust error handling mechanisms to prevent system instability from simple malformed requests. This weakness can be mapped to ATT&CK technique T1499.004 which covers network denial of service attacks, emphasizing the critical nature of maintaining system stability against remotely exploitable conditions in enterprise network infrastructure.