CVE-2023-52656

What it actually does

Presence of dead code in io_uring for SCM_RIGHTS file descriptor passing after support was dropped, which can be triggered locally to cause denial of service via kernel instability or resource mishandling.

Why it matters to the business

Affected Linux systems may experience unexpected crashes or service unavailability from local interactions, increasing downtime risk in environments with high Ubuntu kernel deployment.

How an attack unfolds

A local attacker triggers the remaining SCM_RIGHTS handling code paths in io_uring to induce a kernel fault or availability impact without needing network access or elevated privileges.

How to fix it

Upgrade affected packages to the listed fixed versions including linux 3.11.0-12.19 and linux-aws-5.4 5.4.0-1120.130~18.04.1 or newer releases that remove the dead code.

How to confirm the fix worked

Confirm the running kernel matches or exceeds the fixed package versions and verify absence of SCM_RIGHTS io_uring code in the io_uring subsystem via source inspection or runtime testing.

Typical attack path

1. Obtain local shell or process execution on target system
2. Invoke io_uring operations involving file descriptor passing
3. Reach the dead SCM_RIGHTS code paths
4. Trigger kernel-level denial of service

How to detect it

Review system and kernel logs for io_uring faults, crashes, or warnings referencing SCM_RIGHTS or file descriptor passing after the published date.

What your security team should do

• Apply kernel updates to fixed versions immediately on all affected Ubuntu systems
• Audit applications using io_uring for local attack surface reduction
• Monitor kernel logs for io_uring related faults until patches are deployed