Is CVE-2026-66279 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-66279 being exploited in the wild.

How severe is CVE-2026-66279?

Informational severity, published 22 October 2026.

Which products and versions are affected?

Silicon Labs Connect SDK 4.3.3 and earlier; Silicon Labs Flex SDK 3.7.7 and earlier.

Is there a fix for CVE-2026-66279?

Yes: fixed in Connect SDK included in SiSDK 2026.6.2 or later; Flex SDK included in GSDK 4.5.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-66279 attacked?

It is attacked from the adjacent network, in a software library.

Am I affected by CVE-2026-66279?

Check whether you run Silicon Labs Connect SDK or Silicon Labs Flex SDK 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-2026-66279: Silicon Labs Connect SDK and Flex SDK authentication bypass in MAC parser

CVE-2026-66279 · Severity: info · Published 2026-10-22

Silicon Labs Connect SDK and Flex SDK are wireless networking SDKs used in embedded IoT devices. A flaw in how these SDKs validate message authentication allows an attacker on the network to bypass authentication checks and send spoofed messages, potentially disrupting network operations or resetting devices without gaining access to encryption keys or network traffic.

Vendors: Silicon Labs.

Quick answers

Is CVE-2026-66279 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-66279 being exploited in the wild.
How severe is CVE-2026-66279?: Informational severity, published 22 October 2026.
Which products and versions are affected?: Silicon Labs Connect SDK 4.3.3 and earlier; Silicon Labs Flex SDK 3.7.7 and earlier.
Is there a fix for CVE-2026-66279?: Yes: fixed in Connect SDK included in SiSDK 2026.6.2 or later; Flex SDK included in GSDK 4.5.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-66279 attacked?: It is attacked from the adjacent network, in a software library.
Am I affected by CVE-2026-66279?: Check whether you run Silicon Labs Connect SDK or Silicon Labs Flex SDK 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.

How to fix

Fixed in: Connect SDK included in SiSDK 2026.6.2 or later; Flex SDK included in GSDK 4.5.1 or later

Technical details

The vulnerability stems from improper validation of the MAC security field in the SDK's message parser, allowing malformed authentication messages to be accepted without proper verification. An adjacent network attacker can send crafted messages to spoof legitimate network commands, potentially causing denial of service or unauthorized configuration changes. The vulnerability does not compromise encryption or grant access to the network key.

Affected products

Silicon Labs Connect SDK 4.3.3 and earlier
Silicon Labs Flex SDK 3.7.7 and earlier

Timeline

2026-10-22: disclosed

References

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