CVE-2026-11405
Hidden backdoor authentication mechanism in multiple versions of Tenda firmware allows admin access to web management interface
- State
- Published
- Severity
- 9.8 Critical
- Published
- Jul 6, 2026
- Updated
- Jul 8, 2026
- Reserved
- Jun 5, 2026
Description
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
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | CISA-ADP |
Weaknesses
The record names no weakness.
Affected Products
| Product | Versions |
|---|---|
firmwareTenda |
|
firmwareTenda |
|
firmwareTenda |
|
firmwareTenda |
|
firmwareTenda |
|
References
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