The CVE-2026-27513 vulnerability is a cross-site request forgery (CSRF) flaw found in the web-based administrative interface of the Shenzhen Tenda F3 wireless router firmware version V12.01.01.55_multi. CSRF vulnerabilities occur when a web application does not implement sufficient protections to verify that state-changing requests originate from legitimate users. In this case, the Tenda F3 router’s interface lacks anti-CSRF tokens or similar mechanisms, allowing an attacker to craft malicious web pages that, when visited by an authenticated administrator, cause the browser to unknowingly submit unauthorized requests to the router. These requests can modify router configurations such as network settings, firewall rules, or administrative credentials. The attack requires no privileges or authentication by the attacker but does require the victim administrator to be logged into the router’s interface and to interact with a malicious site, typically via social engineering. The CVSS 4.0 vector indicates network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but user interaction is required (UI:A). The impact is primarily on integrity and confidentiality, as unauthorized configuration changes can compromise network security and data privacy. There are no reported exploits in the wild, and no patches are currently linked, indicating the need for vendor action. The vulnerability is classified under CWE-352, a common web security weakness related to CSRF.

This vulnerability can have significant impacts on organizations using the affected Tenda F3 routers. Unauthorized configuration changes can lead to compromised network security, including altered firewall rules, changed DNS settings, or exposure of sensitive network segments. Attackers could redirect traffic, disable security features, or create backdoors, potentially facilitating further attacks or data exfiltration. Since the router is a critical network infrastructure component, such unauthorized changes can disrupt business operations and compromise confidentiality and integrity of internal communications. The requirement for an authenticated administrator to be tricked into visiting a malicious webpage limits the ease of exploitation but does not eliminate risk, especially in environments where administrators may access untrusted sites. The absence of known exploits suggests limited current exploitation, but this could change once exploit code becomes publicly available. Organizations relying on Tenda F3 routers in sensitive or high-security environments face elevated risks.

To mitigate this vulnerability, organizations should first monitor for firmware updates from Shenzhen Tenda Technology Co., Ltd. that address the CSRF issue and apply them promptly. In the absence of patches, network administrators should restrict access to the router’s administrative interface to trusted management networks only, using VLAN segmentation or firewall rules to prevent exposure to untrusted networks or the internet. Implementing multi-factor authentication (MFA) for router administration can reduce the risk of unauthorized access. Administrators should be trained to avoid visiting untrusted websites while logged into router interfaces and to log out immediately after configuration tasks. Network-level protections such as web filtering and endpoint security can help block malicious sites used in CSRF attacks. Additionally, organizations can consider replacing vulnerable hardware with devices that implement robust security controls if patching is not feasible. Regular auditing of router configurations can help detect unauthorized changes early.