Is CVE-2026-121609 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-121609 being exploited in the wild.

How severe is CVE-2026-121609?

Critical severity, with a CVSS score of 10, published 4 November 2026.

Which products and versions are affected?

Qihoo 360 Whole Home Router M5 4.0.17.1566; Qihoo 360 Whole Home Router M50 4.0.17.1566.

Is there a fix for CVE-2026-121609?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-121609 attacked?

It is attacked with local access, in a network appliance.

Am I affected by CVE-2026-121609?

Check whether you run Qihoo 360 Whole Home Router M5 or Qihoo 360 Whole Home Router M50 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.

CVE-2026-121609: Qihoo 360 Whole Home Router M5 hard-coded root credentials in boot script

CVE-2026-121609 · Severity: critical · CVSS 10 · Published 2026-11-04

The Qihoo 360 Whole Home Router M5 contains a hard-coded root password in its boot script that is set automatically when the device is in factory state, combined with an unconditionally enabled telnet service. An attacker on the local network can connect to the telnet service and gain unauthenticated root shell access, enabling arbitrary command execution, file manipulation, and persistent backdoor installation on the home network device.

Vendors: Qihoo 360.

Quick answers

Is CVE-2026-121609 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-121609 being exploited in the wild.
How severe is CVE-2026-121609?: Critical severity, with a CVSS score of 10, published 4 November 2026.
Which products and versions are affected?: Qihoo 360 Whole Home Router M5 4.0.17.1566; Qihoo 360 Whole Home Router M50 4.0.17.1566.
Is there a fix for CVE-2026-121609?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-121609 attacked?: It is attacked with local access, in a network appliance.
Am I affected by CVE-2026-121609?: Check whether you run Qihoo 360 Whole Home Router M5 or Qihoo 360 Whole Home Router M50 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 exists in /etc/init.d/mpt where, in factory state, the boot script unconditionally sets the root password to the hard-coded value "12345678" and starts an unauthenticated telnet service on port 23. The attack is reachable from the local network (AV:A) without authentication or user interaction, requiring only that the device remain in uninitialized state (mptdone flag not yet written). An attacker gains immediate root-level code execution with uid=0.

Affected products

Qihoo 360 Whole Home Router M5 4.0.17.1566
Qihoo 360 Whole Home Router M50 4.0.17.1566

Timeline

2026-11-04: disclosed
2026-09-25: advisory: Vendor notified via 360SRC

References

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