CVE-2026-98018 Linux CVE debrief

Who should care

Linux kernel developers, maintainers, and users of Linux-based systems should assess exposure and apply patches as necessary. Linux kernel developers and maintainers are responsible for patching the vulnerability, while users of Linux-based systems should verify their kernel versions and apply patches if necessary.

Why it matters

CVE-2026-98018 is a vulnerability in the Linux kernel that requires patching to prevent potential issues. Linux kernel developers, maintainers, and users should assess exposure and apply patches as necessary.

• Verify Linux kernel versions and apply patches to prevent potential use-after-free issues.
• Monitor system logs for exploitation attempts related to this vulnerability.

Technical summary

The mctp_i3c_probe function in the Linux kernel does not hold the busdevs_lock long enough, allowing for a potential use-after-free issue when I3C_NOTIFY_BUS_REMOVE is triggered concurrently. This can lead to adding a list node through a freed mbus pointer. The issue arises from a race condition between the mctp_i3c_probe function and I3C_NOTIFY_BUS_REMOVE, which can unregister and free the bus netdev before the probe function completes. To address this, the busdevs_lock should be held until the device has been added.

Defensive priority

Medium

Recommended defensive actions

• Review and apply the provided kernel patches to ensure the vulnerability is addressed.
• Verify that the Linux kernel version in use is not affected by this vulnerability.
• Monitor system logs for potential exploitation attempts.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Evidence notes

The CVE record and source references indicate a race condition in the Linux kernel's mctp_i3c_probe function. Holding busdevs_lock until device addition prevents use-after-free issues. This vulnerability requires patching to prevent potential use-after-free issues. Linux kernel developers, maintainers, and users should assess exposure and apply patches as necessary. The issue arises from a race condition between the mctp_i3c_probe function and I3C_NOTIFY_BUS_REMOVE, which can unregister and free the bus netdev before the probe passes.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.