CVE-2025-31355 in AC6
Summary
by MITRE • 08/20/2025
A firmware update vulnerability exists in the Firmware Signature Validation functionality of Tenda AC6 V5.0 V02.03.01.110. A specially crafted malicious file can lead to arbitrary code execution. An attacker can provide a malicious file to trigger this vulnerability.
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Analysis
by VulDB Data Team • 08/20/2025
The vulnerability identified as CVE-2025-31355 represents a critical security flaw within the firmware signature validation mechanism of Tenda AC6 V5.0 V02.03.01.110 wireless routers. This issue resides in the firmware update process where the device fails to properly validate the authenticity and integrity of firmware images before installation. The vulnerability stems from insufficient cryptographic validation checks that allow malicious actors to bypass the normal firmware verification procedures. The affected device operates under the assumption that any firmware image presented to it is legitimate, creating a dangerous attack surface where unauthorized code can be executed on the device. This flaw directly impacts the device's ability to maintain secure firmware integrity, which is fundamental to network security infrastructure.
The technical implementation of this vulnerability demonstrates a clear failure in the firmware update protocol's cryptographic validation layer. When a firmware update is initiated, the device should verify the digital signature of the firmware image against a trusted certificate authority or public key. However, in this case, the validation process contains a critical logic flaw that permits malformed or unsigned firmware images to proceed with installation. The vulnerability likely exists in the firmware parser or signature verification routine where insufficient input sanitization allows attackers to craft malicious firmware files that appear valid to the device's validation system. This type of vulnerability typically maps to CWE-310, which covers cryptographic issues related to signature validation and authentication failures. The attack vector requires an authenticated user to provide a malicious firmware file, making this a privilege escalation vulnerability that could be leveraged by attackers with network access.
The operational impact of this vulnerability extends far beyond simple device compromise, creating a significant threat to entire network infrastructures. Once arbitrary code execution is achieved, attackers can modify the router's functionality to redirect traffic, install backdoors, or create persistent access points within the network. The compromised device becomes a potential pivot point for lateral movement attacks against internal network segments, as routers often serve as critical network boundary devices. Network administrators may remain unaware of the compromise since the malicious firmware can be configured to operate silently, maintaining normal network operations while conducting unauthorized activities. This vulnerability particularly affects enterprise and home network environments where router security is often overlooked, creating a potential pathway for advanced persistent threats to establish long-term presence within target networks. The attack could be executed through various means including web-based firmware upload interfaces or direct network protocols, depending on the specific implementation details.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. The primary recommendation involves updating to firmware versions that properly implement cryptographic signature validation and input sanitization. Device manufacturers should implement robust validation routines that check for proper digital signatures and enforce strict integrity checks before allowing firmware installation. Network administrators should consider implementing network segmentation and monitoring to detect anomalous behavior that might indicate compromise. Additionally, regular firmware audits and secure update procedures should be established to prevent unauthorized modifications. The vulnerability highlights the importance of secure boot processes and proper cryptographic implementation as outlined in the NIST SP 800-155 standard for firmware security. Organizations should also consider implementing network access controls and intrusion detection systems to monitor for suspicious firmware update activities. Given the nature of this vulnerability, which involves privilege escalation through firmware manipulation, defense in depth strategies including network monitoring, regular security assessments, and endpoint protection measures become essential components of a comprehensive security posture. The vulnerability serves as a reminder of the critical importance of secure firmware development practices and proper validation mechanisms in network infrastructure devices.