CVE-2026-27514 is a vulnerability identified in the firmware of the Shenzhen Tenda F3 wireless router, specifically version V12.01.01.55_multi. The issue arises from the configuration download functionality, which returns sensitive information—namely the router password and administrative password—in plaintext within the HTTP response. This exposure violates secure handling of sensitive data and is classified under CWE-201 (Insertion of Sensitive Information Into Sent Data) and CWE-525 (Information Exposure Through Cache). Furthermore, the HTTP response omits Cache-Control directives, which would normally prevent sensitive data from being stored in client-side caches such as browser caches or proxy caches. As a result, any user or process with access to the local cache can retrieve these passwords, increasing the risk of unauthorized access. 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), and no user interaction (UI:N). The vulnerability impacts confidentiality severely but does not affect integrity or availability. No patches or exploits are currently known, but the risk remains significant due to the sensitive nature of the exposed data and ease of exploitation within a local network or remotely if management interfaces are exposed. This vulnerability highlights the importance of secure firmware design, proper handling of sensitive data, and appropriate HTTP header configurations to prevent caching of confidential information.

The primary impact of CVE-2026-27514 is the compromise of confidentiality of router credentials, which can lead to unauthorized administrative access to the affected Tenda F3 routers. Once an attacker obtains these credentials, they can alter router configurations, intercept or redirect network traffic, deploy malware, or create persistent backdoors within the network. This can compromise the security of all devices connected to the router, potentially leading to data breaches, network disruptions, or further lateral movement within an organization’s infrastructure. The omission of Cache-Control headers exacerbates the risk by allowing sensitive data to be stored in browser or proxy caches, increasing the attack surface to local users or malware on client machines. Organizations relying on these routers, especially in small to medium business or home office environments where security controls may be limited, face elevated risks of network compromise. The vulnerability’s ease of exploitation without user interaction and low privilege requirements further increase its threat level. Although no active exploits are reported, the potential for credential theft and subsequent attacks makes this a critical issue to address promptly.

To mitigate CVE-2026-27514, organizations should first check for firmware updates from Shenzhen Tenda Technology that address this vulnerability and apply them immediately once available. In the absence of patches, restrict access to the router’s management interface by limiting it to trusted IP addresses or disabling remote management features. Change default and existing router passwords to strong, unique credentials and consider implementing network segmentation to isolate critical devices from vulnerable routers. Clear browser and proxy caches regularly to remove any stored sensitive data and configure client devices to avoid caching sensitive HTTP responses where possible. Network administrators should monitor router logs and network traffic for unusual access patterns or configuration changes. Employ network-level protections such as firewalls and intrusion detection/prevention systems to detect and block unauthorized access attempts. Finally, educate users about the risks of accessing router management interfaces from untrusted networks and the importance of maintaining updated firmware and secure configurations.