CVE-2026-11405
Hidden backdoor authentication mechanism in multiple versions of Tenda firmware allows admin access to web management interface
Tenda·firmware
- Published
- Jul 6, 2026
- Updated
- Jul 8, 2026
- First covered
- Jul 7, 2026
- Latest story
- 4 months ago
Summary
The web server binary /bin/httpd contains a hidden backdoor authentication mechanism in the login() function at 004c88b8.- The function contains a normal authentication path using MD5/hash-based password verification (prod_encode64/PasswordToMd5/check_rand_key). - After normal authentication fails, it calls GetValue("sys.rzadmin.password") to read a backdoor password from the device configuration. - It performs a direct strcmp() comparison (plaintext, not hashed) between the config value and the user-supplied password.A successful match grants role=2 (admin-level access) and creates a valid session. The rzadmin username is never checked — any username works with the backdoor
Attack profile
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
- Tenda firmwareUS_AC6V2.0RTL_V15.03.06.51_multi_T
- Tenda firmwareUS_AC5V1.0RTL_V15.03.06.48_multi_TDE01
- Tenda firmwareUS_AC10V1.0re_V15.03.06.46_multi_TDE01
- Tenda firmwareUS_W15EV1.0br_V15.11.0.5(1068_1567_841)_EN_TDE
- Tenda firmwareUS_FH1201V1.0BR_V1.2.0.14(408)_EN_TD