CVE-2026-86150 in CP3
Summary
by MITRE • 09/06/2026
A security vulnerability has been detected in Tenda CP3 27.5.57.101. Impacted is an unknown function of the file custom-x/softap/hostapd. Such manipulation of the argument wpa_passphrase leads to hard-coded credentials. The attack can be launched remotely. The exploit has been disclosed publicly and may be used.
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Analysis
by VulDB Data Team • 09/06/2026
The Tenda CP3 router, specifically version 27.5.57.101, contains a critical security flaw within its wireless access point configuration module located in the custom-x/softap/hostapd component. This vulnerability stems from improper handling of the wpa_passphrase argument during the device's initialization or reconfiguration processes. Instead of securely generating and storing a unique cryptographic key derived from user-provided input, the system fails to properly sanitize or validate this parameter before applying it to the host access point daemon configuration. Consequently, when an attacker manipulates this specific argument through remote network interactions, they can force the device into a state where it utilizes hardcoded credentials rather than dynamically generated secure keys. This behavior represents a severe deviation from standard security practices for wireless authentication protocols and fundamentally undermines the confidentiality of communications protected by WPA or WPA2 encryption standards.
From a technical perspective, this flaw aligns with CWE-798: Use of Hard-coded Credentials, as well as CWE-156: Incorrect Specification of Default Value. The root cause lies in the software logic that processes wireless security parameters without enforcing strict input validation or ensuring that default fallback mechanisms do not expose static secrets. By exploiting this condition remotely, an adversary can bypass the intended authentication barrier entirely. Since the exploit has been publicly disclosed and is known to be functional, threat actors are actively leveraging this weakness to gain unauthorized access to affected devices on local networks. The ability to launch such attacks remotely means that physical proximity or prior network compromise is not required for initial exploitation, significantly lowering the barrier to entry for malicious actors targeting IoT infrastructure in residential or small business environments.
The operational impact of this vulnerability is substantial and multifaceted. Once an attacker successfully exploits the hardcoded credential flaw, they can authenticate as a legitimate user on the wireless network without knowing the actual passphrase set by the administrator. This grants them full access to all devices connected to that Wi-Fi segment, enabling activities such as traffic interception, man-in-the-middle attacks, lateral movement into internal networks, and potential control of other IoT endpoints sharing the same broadcast domain. Furthermore, because many home routers also serve as gateways to broader network segments including local file shares or smart home ecosystems, this breach can lead to widespread data exfiltration and privacy violations. The persistence of hardcoded credentials means that even if an administrator attempts to change their password through standard interfaces, the underlying vulnerability may still allow attackers to bypass these changes by exploiting the same flawed logic in the hostapd configuration handler.
Mitigation strategies must address both immediate remediation and long-term security posture improvements. Users should immediately update their Tenda CP3 firmware to a patched version that corrects the input validation logic within the softap/hostapd module, ensuring that passphrase arguments are properly sanitized and do not trigger hardcoded credential fallback mechanisms. In cases where updating is not immediately feasible, network segmentation techniques such as VLAN isolation can help limit the blast radius of a potential compromise by separating IoT devices from critical internal resources. Additionally, administrators should enforce strong, complex passphrases to mitigate risks associated with other weak authentication practices, although this does not fully resolve the underlying code defect. Monitoring network traffic for anomalous connection attempts or unauthorized device associations can also aid in early detection of exploitation activities. Industry standards such as OWASP IoT Top 10 highlight similar issues under categories related to insecure default configurations and lack of secure update mechanisms, emphasizing the need for manufacturers to implement rigorous security testing before releasing firmware updates that handle sensitive authentication parameters.