CVE-2025-55972 in Smart TV
Summary
by MITRE • 10/03/2025
A TCL Smart TV running a vulnerable UPnP/DLNA MediaRenderer implementation is affected by a remote, unauthenticated Denial of Service (DoS) condition. By sending a flood of malformed or oversized SetAVTransportURI SOAP requests to the UPnP control endpoint, an attacker can cause the device to become unresponsive. This denial persists as long as the attack continues and affects all forms of TV operation. Manual user control and even reboots do not restore functionality unless the flood stops.
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Analysis
by VulDB Data Team • 10/04/2025
This vulnerability affects TCL Smart TVs that implement the UPnP/DLNA MediaRenderer protocol, creating a remote and unauthenticated denial of service condition that can completely incapacitate the device. The flaw resides in the UPnP control endpoint implementation where the device fails to properly validate incoming SOAP requests, specifically the SetAVTransportURI method that is used to control media playback. When an attacker sends a flood of malformed or oversized SOAP requests to the vulnerable endpoint, the device's processing capabilities become overwhelmed, leading to complete system unresponsiveness. The attack does not require any authentication credentials or network proximity, making it particularly dangerous as any remote attacker can exploit this weakness. The vulnerability demonstrates a classic lack of input validation and resource management in the UPnP implementation, where the device does not properly handle malformed XML payloads or excessive request sizes, causing the underlying process to become stuck or crash.
The technical impact of this vulnerability extends beyond simple service interruption as it affects all aspects of TV operation including the user interface, media playback controls, network connectivity, and even the device's ability to respond to manual user inputs. The device becomes completely unresponsive to both remote UPnP commands and local user interactions, rendering it effectively unusable until the attack ceases. This behavior indicates that the vulnerability likely causes a critical system resource exhaustion or process lockup within the UPnP service implementation. The persistence of the denial of service condition means that even traditional recovery mechanisms such as manual device reboot do not restore normal operation until the malicious request flood stops, suggesting that the attack may be overwhelming system resources or corrupting critical process states. This vulnerability directly maps to CWE-400, which covers "Uncontrolled Resource Consumption" and potentially CWE-770, "Allocation of Resources Without Limits or Throttling," as the device lacks proper rate limiting and resource management for incoming UPnP requests.
From an operational perspective, this vulnerability represents a significant risk to consumer devices in home networks, as it allows remote attackers to completely disable television functionality without requiring any specialized tools or network access beyond basic internet connectivity. The attack can be executed from anywhere with internet access, making it particularly concerning for IoT devices that are often left unattended and exposed to the internet. The affected devices remain vulnerable as long as the attack continues, meaning that even after a user attempts to restart the device, the system will remain unresponsive until the attacker stops sending requests. Network administrators and security professionals should be aware that this vulnerability can be exploited by attackers who may be attempting to disrupt services or cause inconvenience to consumers. The lack of authentication requirements makes this a particularly dangerous vulnerability, as it can be exploited by anyone with knowledge of the device's network address and UPnP port configuration.
Mitigation strategies for this vulnerability should focus on network-level protections and device-specific configurations. Organizations and individuals should implement firewall rules that restrict access to UPnP ports and services, particularly on devices that do not require external UPnP access. The most effective immediate solution involves disabling UPnP functionality entirely on affected TCL Smart TVs if the feature is not required for normal operation. Network administrators should consider implementing rate limiting or request throttling mechanisms at the network perimeter to prevent the flood of requests from overwhelming individual devices. Device manufacturers should be encouraged to provide firmware updates that implement proper input validation, request size limits, and resource consumption monitoring for UPnP services. Additionally, security monitoring should include detection of unusual UPnP traffic patterns that may indicate exploitation attempts. This vulnerability aligns with ATT&CK technique T1499.004, "Endpoint Denial of Service," and demonstrates how IoT devices can become easy targets for remote exploitation due to insufficient security controls and lack of proper resource management in embedded services. The vulnerability also highlights the importance of secure coding practices in embedded systems and the need for proper input validation and resource management in network services, particularly those that are exposed to untrusted networks.