Is CVE-2026-5611 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-5611 being exploited in the wild.

How severe is CVE-2026-5611?

High severity, with a CVSS score of 8.8, published 6 April 2026.

Is there a fix for CVE-2026-5611?

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-2026-5611 attacked?

It is attacked over the network, in device firmware.

Am I affected by CVE-2026-5611?

Check whether you run Belkin F9k1015 or Belkin F9k1015 Firmware 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-2026-5611: Belkin F9K1015 stack-based buffer overflow in formCrossBandSwitch

CVE-2026-5611 · Severity: high · CVSS 8.8 · Published 2026-04-06

A security vulnerability exists in the Belkin F9K1015 wireless router, a device used to provide internet connectivity in homes and small offices. An attacker can exploit this flaw to crash the router or potentially take full control of the device by sending a specially crafted web request. This could lead to a complete loss of internet service or unauthorized access to the network traffic passing through the router.

Technologies: Belkin F9k1015, Belkin F9k1015 Firmware. Vendors: Belkin.

Quick answers

Is CVE-2026-5611 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-5611 being exploited in the wild.
How severe is CVE-2026-5611?: High severity, with a CVSS score of 8.8, published 6 April 2026.
Which products and versions are affected?: Belkin F9k1015 1.00.10.
Is there a fix for CVE-2026-5611?: 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-2026-5611 attacked?: It is attacked over the network, in device firmware.
Am I affected by CVE-2026-5611?: Check whether you run Belkin F9k1015 or Belkin F9k1015 Firmware 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

A stack-based buffer overflow vulnerability exists in the 'formCrossBandSwitch' function within the '/goform/formCrossBandSwitch' component of Belkin F9K1015 firmware version 1.00.10. The vulnerability is caused by an unsafe 'strcpy' operation where the user-supplied 'webpage' parameter is copied into a fixed-size stack buffer ('reboot_msg') without adequate length validation. A remote attacker with low privileges can exploit this by sending a crafted POST request, leading to a denial of service (system crash) or potential remote code execution. A public exploit (PoC) is available, and the vendor has reportedly not responded to disclosure attempts.

Affected products

Belkin F9K1015 1.00.10

Timeline

2026-04-05: disclosed: Initial disclosure via VulDB
2026-04-06: advisory: NVD publication date

References

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