WNC T-Mobile 5G Box routers get root RCE flaws
Six vulnerabilities in WNC T-Mobile 5G Box IDU routers allow unauthenticated attackers to bypass auth, steal credentials, and gain root via command injection.
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What to check
- Applies to
- The 6 CVEs named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
CERT Polska coordinated disclosure of six vulnerabilities affecting WNC (Wistron NeWeb Corporation) T-Mobile 5G Box IDU routers. The flaws span authentication bypass, unauthenticated information disclosure, CSRF, and multiple OS command injection vulnerabilities in the portal.cgi and wnc_maccheck.cgi components. Most severe are CVE-2026-58146, which allows a remote, unauthenticated attacker to inject shell commands via the cli_cookie POST parameter and gain root access, and CVE-2026-40856, which exposes the admin web password, WiFi passphrase, and device configuration data without any authentication via the wnc_maccheck.cgi endpoint.
Additional issues include CVE-2026-40854, an authentication bypass in the session validation logic that trusts a sessionid cookie mapped to files in /tmp/login_user and can be manipulated using directory traversal sequences ("."/"..") to gain unauthorized admin panel access; CVE-2026-40855, a command injection in the ping diagnostic feature (ping_ip, ping_size, ping_times parameters) requiring authentication but yielding root shell access; CVE-2026-40857, a CSRF flaw where the anti-CSRF token is not properly validated, enabling attacker-controlled actions via a malicious webpage visited by an authenticated user; and CVE-2026-58147, an OS command injection in the password-change functionality via the http_passwd_hidden and http_passwdConfirm_hidden parameters, exploitable by an authenticated user for root-level command execution.
Chained together, an unauthenticated attacker could use CVE-2026-40856 or CVE-2026-40854 to obtain credentials or admin access, then leverage CVE-2026-58146, CVE-2026-40855, or CVE-2026-58147 for full root compromise of the device. All issues are fixed in firmware version 1.1.0.651412. Defenders operating these devices, likely deployed as consumer/SME 5G CPE by T-Mobile, should prioritize immediate firmware update and restrict management interface exposure to untrusted networks in the interim. No in-the-wild exploitation has been reported at time of disclosure.
Mentioned in this report
Source reporting: https://cert.pl/en/posts/2026/09/CVE-2026-40854
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