CVE-2026-27511 is a clickjacking vulnerability identified in the Shenzhen Tenda F3 wireless router firmware version V12.01.01.55_multi. The root cause is the absence of the X-Frame-Options HTTP header or equivalent frame-busting mechanisms in the router's web-based administrative interface. This omission allows malicious websites to embed the router's admin pages within an iframe. When an authenticated administrator visits such a malicious site, they can be tricked into clicking on hidden or disguised UI elements within the iframe, causing unintended administrative actions such as configuration changes. The vulnerability is classified under CWE-1021, which pertains to improper restriction of rendered UI layers or frames. The CVSS v4.0 base score is 5.1 (medium), reflecting that the attack vector is network-based, requires no privileges or authentication, but does require user interaction. The impact on confidentiality and integrity is low to moderate, as unauthorized configuration changes could compromise network security. There is no impact on availability, and no known exploits have been reported. No patches or official mitigations have been released by Shenzhen Tenda Technology Co., Ltd. as of the publication date. This vulnerability highlights the importance of implementing frame-busting headers such as X-Frame-Options or Content-Security-Policy frame-ancestors directives in web interfaces to prevent clickjacking attacks.

The primary impact of this vulnerability is the potential for unauthorized configuration changes to the Tenda F3 router by tricking an authenticated administrator into performing unintended actions. Such changes could weaken network security, expose internal networks, or disrupt normal operations. Although the vulnerability does not directly compromise availability or confidentiality of data, unauthorized configuration modifications can lead to further exploitation or network compromise. Organizations relying on Tenda F3 routers, especially in small office or home office environments, may face increased risk of network infiltration or persistent attacks if exploited. The requirement for user interaction limits the ease of exploitation, but social engineering tactics can increase success rates. Since no patches are currently available, the risk remains until mitigations are applied. The absence of known exploits in the wild suggests limited active targeting but does not preclude future exploitation attempts.

To mitigate this vulnerability, organizations should implement the following specific measures: 1) Restrict access to the router's administrative interface by limiting it to trusted internal networks and disabling remote management where possible. 2) Use network segmentation and firewall rules to prevent access to the router's web interface from untrusted sources. 3) Educate administrators about the risks of clicking links or visiting untrusted websites while logged into router management interfaces. 4) Employ browser extensions or security settings that block or warn about framed content from untrusted origins. 5) Monitor router configurations regularly for unauthorized changes to detect potential exploitation. 6) Contact Shenzhen Tenda Technology Co., Ltd. for updates or firmware patches addressing this vulnerability and apply them promptly once available. 7) Consider replacing affected devices with models that implement proper frame-busting headers and security controls if no timely patch is provided. These targeted mitigations go beyond generic advice by focusing on access control, user awareness, and proactive monitoring specific to this clickjacking risk.