CVE-2026-80951

A flaw was found in the Linux kernel's I3C master driver. A malicious I3C device could exploit this by sending an In-Band Interrupt (IBI) payload that exceeds the allocated slot size. This can lead to an out-of-bounds write into the IBI pool, potentially causing memory corruption and system instability.

This vulnerability is rated as Important because an out-of-bounds kernel memory write can lead to a system crash or arbitrary code execution with kernel privileges. Triggering the flaw requires physical access to an attached malicious device operating on an I3C bus managed by the Silvaco controller driver. Most enterprise Red Hat Enterprise Linux server and cloud environments do not utilize this specialized bus hardware, substantially limiting practical exposure across standard installations.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this vulnerability, prevent the Silvaco I3C master controller driver module from loading:

1. Blacklist the kernel module:

echo "blacklist svc-i3c-master" >> /etc/modprobe.d/blacklist-svc-i3c-master.conf

2. Configure the module to fail loading if called directly or as a dependency:

echo "install svc-i3c-master /bin/false" >> /etc/modprobe.d/blacklist-svc-i3c-master.conf

Caveats: Disabling this module prevents the system from communicating with Silvaco I3C master hardware controllers and attached I3C peripherals. If the module is currently loaded, a system reboot is required to ensure it is completely unloaded from memory.