The vulnerability identified as CVE-2026-27514 affects the Shenzhen Tenda F3 wireless router firmware version V12.01.01.55_multi. It is categorized under CWE-201 (Insertion of Sensitive Information Into Sent Data) and CWE-525 (Information Exposure Through Cache). The issue arises in the router's configuration download functionality, where the response payload includes sensitive credentials such as the router password and administrative password in plaintext. This exposure occurs because the firmware does not sanitize or encrypt these sensitive fields before sending them to the client. Furthermore, the HTTP response lacks appropriate Cache-Control directives, which means that browsers or other client-side applications may cache this sensitive information locally. This cached data can then be accessed by other users or processes on the same device, increasing the risk of credential theft. The vulnerability has a CVSS 4.0 base score of 7.1, indicating high severity, with an attack vector of network (AV:N), low attack complexity (AC:L), no privileges required (PR:L - low privileges), no user interaction (UI:N), and high impact on confidentiality (VC:H). The flaw does not affect integrity or availability but compromises confidentiality significantly. No patches or fixes are currently linked, and no known exploits have been reported in the wild. The vulnerability's exploitation could allow attackers to retrieve plaintext credentials remotely, potentially leading to unauthorized administrative access to the router and subsequent network compromise.

The primary impact of CVE-2026-27514 is the exposure of sensitive router and administrative passwords in plaintext, which can lead to unauthorized access to the affected Tenda F3 routers. Once attackers obtain these credentials, they can gain full administrative control over the device, enabling them to alter configurations, intercept or redirect network traffic, deploy malware, or create persistent backdoors. The lack of Cache-Control headers exacerbates the risk by allowing sensitive data to be stored in client-side caches, potentially exposing credentials to other local users or malicious processes on the same machine. This vulnerability threatens the confidentiality of network credentials and can compromise the security of entire networks relying on these routers. Organizations using these devices, especially in environments with multiple users sharing client devices, face increased risk of lateral movement and data breaches. Given the widespread use of Tenda routers in residential and small business environments, the vulnerability could facilitate large-scale unauthorized access if exploited at scale.

To mitigate CVE-2026-27514, organizations and users should immediately check for firmware updates from Shenzhen Tenda Technology Co., Ltd. addressing this vulnerability and apply them as soon as they become available. In the absence of official patches, users should disable the configuration download functionality if possible or restrict access to it via network segmentation or firewall rules limiting access to trusted IP addresses only. Administrators should enforce strong, unique passwords and consider changing router credentials after mitigation steps. Additionally, users should clear browser caches regularly and configure browsers to avoid caching sensitive data, especially when accessing router management interfaces. Network administrators should monitor network traffic for unauthorized access attempts to router management endpoints. Employing network-level protections such as VPNs or management VLANs can reduce exposure. Finally, educating users about the risks of shared devices and local cache exposure can help reduce the risk of credential leakage through cached data.