CVE-2026-51601 in CP3
Summary
by MITRE • 07/09/2026
Tenda CP3 V3.0 firmware V31.1.9.91 contains a stack-based buffer overflow in the RTSP service. The device fails to validate the length of the clock= value in the Range header field when processing a PLAY request. An unauthenticated remote attacker who has completed a standard RTSP session handshake can send a PLAY request with an excessively long clock= value to cause the RTSP service to crash.
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Analysis
by VulDB Data Team • 07/09/2026
The vulnerability identified in Tenda CP3 V3.0 firmware version V31.1.9.91 represents a critical stack-based buffer overflow within the RTSP service component of the device. This flaw exists in the processing of the Range header field specifically when handling PLAY requests, where the system fails to properly validate the length of the clock= parameter value. The vulnerability stems from inadequate input validation mechanisms that allow maliciously crafted payloads to exceed the allocated stack buffer space, leading to memory corruption and subsequent service disruption. Such vulnerabilities fall under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental software security weakness that can result in arbitrary code execution or denial of service conditions.
The operational impact of this vulnerability extends beyond simple service disruption as it creates an entry point for remote attackers to compromise the device's RTSP functionality. An attacker needs only to complete the standard RTSP session handshake process, which is typically unauthenticated and widely available, before sending a specially crafted PLAY request containing an excessively long clock= value. This minimal attack vector makes the vulnerability particularly dangerous as it requires no prior authentication credentials or specialized knowledge beyond basic RTSP protocol understanding. The service crash occurs immediately upon processing the malformed request, effectively rendering the RTSP functionality unavailable to legitimate users and potentially exposing the device to further exploitation attempts.
From a cybersecurity perspective, this vulnerability aligns with ATT&CK technique T1210 for exploiting weaknesses in remote services and T1072 for using remote services as attack vectors. The flaw demonstrates poor defensive programming practices where input validation occurs too late in the processing pipeline, allowing malformed data to traverse multiple system layers before causing a buffer overflow condition. Network traffic analysis would reveal the specific PLAY request containing the oversized clock= parameter, typically appearing as a standard RTSP command stream with an abnormally long parameter value that exceeds normal protocol expectations. The device's failure to implement proper bounds checking or input sanitization creates a predictable crash scenario that can be reliably exploited by remote attackers.
Mitigation strategies for this vulnerability should include immediate firmware updates from Tenda to address the buffer overflow condition through proper input validation and length checks on all RTSP header parameters. Network administrators should implement ingress filtering rules to block RTSP traffic at network perimeters where possible, though this approach is less effective given that legitimate users may require RTSP functionality for device management. System hardening measures include disabling unnecessary RTSP services when not actively required, implementing intrusion detection systems to monitor for suspicious RTSP requests, and establishing regular firmware update schedules to address known vulnerabilities before they can be exploited by malicious actors. Additionally, organizations should consider segmenting network devices to limit the potential impact of such vulnerabilities and maintain detailed logs of RTSP activity for security monitoring purposes.