CVE-2026-2148 is a medium-severity information disclosure vulnerability identified in the Tenda AC21 router, firmware version 16.03.08.16. The vulnerability resides in an unspecified function within the /cgi-bin/DownloadFlash endpoint of the device's web management interface. This flaw allows an unauthenticated remote attacker to manipulate the interface and retrieve sensitive information from the device. The vulnerability does not require any privileges or user interaction, making it remotely exploitable over the network with low attack complexity. The disclosed exploit potentially enables attackers to gain access to configuration details, firmware data, or other sensitive information that could facilitate further attacks or network compromise. Although no confirmed exploitation in the wild has been reported, the public availability of exploit details increases the likelihood of future attacks. The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P) reflects network attack vector, no privileges or user interaction required, and low confidentiality impact without integrity or availability effects. The vulnerability is specific to the Tenda AC21 router, a consumer and small business networking device, which is commonly deployed in home and office environments.

For European organizations, this vulnerability poses a risk of unauthorized disclosure of sensitive router information, which could include network configuration, credentials, or firmware details. Such information leakage can facilitate lateral movement, targeted attacks, or network reconnaissance by threat actors. Organizations relying on Tenda AC21 routers for critical network connectivity or management may experience confidentiality breaches, potentially exposing internal network topology or administrative credentials. This could lead to further compromise of internal systems or data exfiltration. Small and medium enterprises, as well as home office setups using these routers, are particularly vulnerable due to potentially weaker network segmentation and security controls. The lack of authentication and user interaction requirements increases the risk of automated exploitation attempts. While the vulnerability does not directly impact integrity or availability, the information disclosure can be a stepping stone for more severe attacks.

1. Monitor Tenda's official channels for firmware updates addressing CVE-2026-2148 and apply patches promptly once available. 2. Restrict access to the router's web management interface by limiting it to trusted internal networks or specific management VLANs. 3. Disable remote management features if not required, especially WAN-side access to the web interface. 4. Implement network segmentation to isolate management interfaces from general user networks. 5. Employ strong, unique administrative passwords and consider multi-factor authentication if supported. 6. Use network intrusion detection systems (NIDS) to monitor for suspicious requests targeting /cgi-bin/DownloadFlash or unusual HTTP activity. 7. Regularly audit router configurations and logs for signs of unauthorized access or information leakage attempts. 8. Educate users and administrators about the risks of exposing management interfaces to untrusted networks. 9. Consider replacing affected devices with models from vendors with more robust security track records if patching is delayed or unsupported.