CVE-2026-40854: high-severity vulnerability in WNC T-Mobile 5G Box IDU
Session auth bypass via cookie value in T-Mobile 5G Box IDU routers
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 0.3%
WNC T-Mobile 5G Box IDU router contains an authentication bypass vulnerability in the portal.cgi component. The session verification mechanism improperly validates the sessionid cookie by checking for the existence of a corresponding file in /tmp/login_user. An attacker can bypass authentication by using directory entries such as "." or ".." in the cookie, allowing unauthorized access to the administration panel.This issue has been fixed in firmware version 1.1.0.651412
CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
WNC · T-Mobile 5G Box IDURelated CVEs — WNC T-Mobile 5G Box IDU
In the same product, most dangerous first.
CVE-2026-58146CRITICALUnauthorized remote code execution in T-Mobile 5G Box IDU routersEPSS 2.9%CVE-2026-40855CRITICALCommand Injection in T-Mobile 5G Box IDU router via ping functionalityEPSS 1.6%CVE-2026-58147CRITICALAuthorized remote code execution via password change functionality in T-Mobile 5G Box IDU routersEPSS 1.6%CVE-2026-40856HIGHConfig disclosure in T-Mobile 5G Box IDU routersEPSS 0.4%CVE-2026-40857HIGHCSRF token bypass in T-Mobile 5G Box IDU routersEPSS 0.2%