Critical Backdoor in Tenda Router Firmware Exposes Networks to Unauthorized Access
In July 2026, a critical vulnerability (CVE-2026-11405) was discovered in multiple Tenda router firmware versions, revealing an undocumented authentication backdoor. This flaw allows attackers to gain administrative access to the device's web management interface without valid credentials, potentially compromising network security. The issue resides in the 'login()' function of the '/bin/httpd' web server binary, where, after standard MD5-based authentication fails, the firmware checks for an alternate password stored in the 'sys.rzadmin.password' configuration. If the supplied password matches this backdoor password, the device grants administrator access regardless of the username entered. Affected firmware versions include those for Tenda FH1201, W15E, AC10, AC5, and AC6 models. As of now, no patches have been released, and Tenda has not responded to communications from security researchers. Users are advised to disable the remote web management panel and restrict local network exposure to mitigate risks. This incident underscores the critical importance of thorough security audits in firmware development and the need for manufacturers to maintain open communication channels with the security community to address vulnerabilities promptly.
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