CVE-2026-11405

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

Affected Software

VendorProductVersion RangeStatus
TendafirmwareUS_AC6V2.0RTL_V15.03.06.51_multi_Taffected
TendafirmwareUS_AC5V1.0RTL_V15.03.06.48_multi_TDE01affected
TendafirmwareUS_AC10V1.0re_V15.03.06.46_multi_TDE01affected
TendafirmwareUS_W15EV1.0br_V15.11.0.5(1068_1567_841)_EN_TDEaffected
TendafirmwareUS_FH1201V1.0BR_V1.2.0.14(408)_EN_TDaffected

Weaknesses

  • CWE-912: Hidden Functionality

ADP Enrichment

CVE Program Container

Additional References

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: total

References