Quick answers
- Is CVE-2026-40856 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-40856 being exploited in the wild.
- How severe is CVE-2026-40856?
- Informational severity, published 16 September 2026.
- Which products and versions are affected?
- WNC T-Mobile 5G Box IDU before 1.1.0.651412.
- Is there a fix for CVE-2026-40856?
- A patch was published on 2026-09-16: Fixed in firmware version 1.1.0.651412 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-40856 attacked?
- It is attacked over the network, in device firmware.
- Am I affected by CVE-2026-40856?
- Check whether you run WNC T-Mobile 5G Box IDU at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a missing authentication for critical function (CWE-306) in the wnc_maccheck.cgi endpoint of WNC T-Mobile 5G Box IDU firmware. The endpoint is accessible without any authentication mechanism and exposes sensitive configuration data via unauthenticated requests. A remote attacker on the network can directly query this endpoint to retrieve administrative credentials, WiFi passphrases, and device configuration information. The attack requires network reachability to the router but no prior authentication or credentials. This issue has been patched in firmware version 1.1.0.651412 and earlier versions are vulnerable.
Affected products
- WNC T-Mobile 5G Box IDU before 1.1.0.651412
Timeline
- 2026-09-16: disclosed
- 2026-09-16: patched: Fixed in firmware version 1.1.0.651412