It looks like recent Tenda hardware/firmware is encrypted per below examples, making it harder to audit.

binwalk US_AC10V6.0si_V16.03.62.09_multi_TDE01.bin

  DECIMAL       HEXADECIMAL     DESCRIPTION
  --------------------------------------------------------------------------------
  516           0x204           OpenSSL encryption, salted, salt: 0x436999A39FECA649

binwalk US_BE12ProV1.0mt_V16.03.66.23_TD01.bin

  DECIMAL       HEXADECIMAL     DESCRIPTION
  --------------------------------------------------------------------------------
  516           0x204           OpenSSL encryption, salted, salt: 0x81235B7D4130B6AB

The third attempt I tried was unencrypted, and possibly reveals the problem exists on another model this CVE doesn't list as affected:

binwalk US_W18EV2_kf_V16.01.0.20\(4766\)_HighPower\ \(1\).bin

  DECIMAL       HEXADECIMAL     DESCRIPTION
  --------------------------------------------------------------------------------
  64            0x40            uImage header, header size: 64 bytes, header CRC: 0x95335734, created: 2026-06-16 09:09:35, image size: 2159135 bytes, Data Address: 0x80100000, Entry Point: 0x805F41C0, data CRC: 0x5ABEDB00, OS: Linux, CPU: MIPS, image type: OS Kernel Image, compression type: lzma, image name: "MIPS Tenda Linux-4.14.90"
  128           0x80            LZMA compressed data, properties: 0x6D, dictionary size: 8388608 bytes, uncompressed size: 6947248 bytes
  2159263       0x20F29F        Squashfs filesystem, little endian, version 4.0, compression:xz, size: 8971644 bytes, 847 inodes, blocksize: 1048576 bytes, created: 2026-06-16 08:53:20

Inside is /squashfs-root/webroot_ro/default_ac.cfg which offers:

  sys.rzadmin.username=rzadmin
  sys.rzadmin.password=cnphZG1pbg==  (ed: base64 decoded: rzadmin)
  sys.guest.username=guest
  sys.guest.password=Z3Vlc3Q=  (ed: base64 decoded: guest)

And /squashfs-root/webroot_ro/default_router.cfg which offers:

  sys.rzadmin.username=rzadmin
  sys.rzadmin.password=cnphZG1pbg==  (ed: base64 decoded: rzadmin)

From what I can see quickly (I haven't looked hard), "sys.rzadmin.password" is only referenced from the login() function of /bin/httpd in the context of retrieving a value. This value is retrieved and compared before the error message "login err: password is wrong." is emitted. I can't find any other reference to code in any part of the firmware that may allow a user to change the default value of "sys.rzadmin.password".

Also for fun there is a function imsd_upload_log_v1 in /bin/imsd that collects SSIDs, MACs, IP addresses, sys.admin.username, sys.rzadmin.username, timezone, and another function imsd_remote_pwd_get in /bin/imsd that retrieves sys.admin.password. Related library /lib/lubucapi.so also looks like a fun binary to inspect more closely as it contains a command set that seemingly allows either cloud management of Tenda routers and/or remote debugging, and possibly is why imsd_remote_pwd_get exists in /bin/imsd

Tenda firmware (multiple versions) contains hidden authentication backdoor