CVE-2026-40857 CSRF token bypass in T-Mobile 5G Box IDU routers
Remote attackers can perform unauthorized actions on T-Mobile 5G Box IDU routers by bypassing CSRF token validation via a malicious website.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-40857?
CVE-2026-40857 is a high-severity vulnerability in WNC T-Mobile 5G Box IDU, published on 16 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
WNC T-Mobile 5G Box IDU router contains a cross-site request forgery (CSRF) vulnerability in the portal.cgi component. The anti-CSRF mechanism fails to validate the csrf_token_value parameter, accepting any arbitrary value as valid. This allows a remote attacker to perform unauthorized actions on the device by tricking an authenticated user into visiting a malicious website.This issue has been fixed in firmware version 1.1.0.651412
Weakness: CWE-352
Which versions are affected by CVE-2026-40857?
How do I fix CVE-2026-40857?
No fix has been published for CVE-2026-40857 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-40857 being exploited?
There is no known exploitation of CVE-2026-40857 in the wild and no public exploit code.
Sources
Also known as GHSA-6v9q-56wf-hqwp.