CVE-2026-40854

8.7 highEPSS 0.3%

High (8.7). EPSS 0.3% chance of exploitation in the next 30 days.

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

Severity

CVSS 4.0

8.7 high

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

EPSS: 0.3% chance of exploitation in the next 30 days; higher than 24% of CVEs (scores of 2026-10-31)
CWE: CWE-290
Published: 2026-09-16
Modified: 2026-09-28
Record from: the NVD, synced 2026-10-19

References

https://cert.pl/posts/2026/09/CVE-2026-40854

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