CVE-2026-98189: wifi: wilc1000: fix RX buffer OOB-write in wilc_wlan_handle_isr_ext()

In plain language

What this advisory means

A security issue was found in the wireless wifi driver for the wilc1000 device in the Azure Linux 3.0 kernel version 6.6.157.1-1. This problem could cause the system to write outside its allowed memory area when processing received wifi data, potentially leading to system instability or other malicious impacts. Microsoft has addressed this issue in a newer kernel version to prevent such problems.

Technical explanation

How the issue affects the environment

The vulnerability involves an out-of-bounds write (OOB-write) in the RX buffer handled by the function wilc_wlan_handle_isr_ext() in the wifi driver for the wilc1000 chipset. When processing interrupt service routines, an incorrect buffer handling could lead to writing past the intended memory boundary, causing memory corruption. This issue is fixed in the later kernel version 6.6.158.1-1 for Azure Linux 3.0, which includes the corrected code to properly manage the RX buffer limits.

Operational impact

Why teams should care

If exploited, this vulnerability could lead to memory corruption in the wireless driver, causing system crashes or potential escalation of privileges. This disruption may impact availability and reliability of systems running affected versions on Azure Linux 3.0, possibly affecting dependent business operations relying on stable wifi connectivity.

Affected and fixed releases

Temporary risk reduction

No separate workaround was supplied in the source feed. Use the official vendor advisory before changing production controls.

Evidence and validation checklist

• Microsoft Security Response Center advisory page for CVE-2026-98189
• Release notes indicating the fix in version 6.6.158.1-1
• Published update link to Azure Linux upgrade instructions from Microsoft.
• No additional exploitation or workaround details provided by Microsoft.