CVE-2022-1786

What it actually does

Use-after-free condition in the Linux kernel io_uring subsystem when a ring is created with IORING_SETUP_IOPOLL and multiple tasks concurrently complete submissions on the same ring, allowing a local process to reference already-freed kernel memory.

Why it matters to the business

Local attackers on affected Linux systems can crash the host or obtain elevated privileges, resulting in full system compromise, service disruption, and potential lateral movement within the environment.

How an attack unfolds

An attacker with local access creates an io_uring ring using IORING_SETUP_IOPOLL, spawns multiple tasks that race to complete submissions, triggers the use-after-free by freeing the ring context, then re-allocates the freed memory with attacker-controlled data to overwrite kernel structures and escalate to root.

How to fix it

Upgrade the Linux kernel to a version containing commit 9f4ad9e425a1d3b6a34617b8ea226d56a119a717 or later; rebuild and reboot all affected hosts with the patched kernel.

How to confirm the fix worked

Verify the running kernel contains commit 9f4ad9e425a1d3b6a34617b8ea226d56a119a717 by checking /proc/version or kernel build logs; confirm absence of the vulnerable io_uring race condition through code review or updated package manifests.

Typical attack path

1. Obtain local unprivileged shell on target system
2. Create io_uring instance with IORING_SETUP_IOPOLL flag
3. Spawn multiple concurrent tasks that submit and complete operations on the ring
4. Trigger race condition that frees the ring context while references remain
5. Reclaim freed memory with controlled data to corrupt kernel structures
6. Execute privilege escalation payload to obtain root access

How to detect it

Review kernel audit logs and process execution records for unusual io_uring ring creation with IOPOLL followed by rapid task forking and memory operations; correlate with privilege escalation events such as unexpected setuid binaries or root shells.

What your security team should do

• Immediately apply the kernel update containing the referenced commit across all production and development systems
• Restrict untrusted local user access until patching is complete
• Monitor for new kernel releases and schedule automated patching pipelines
• Audit systems for custom io_uring usage that may increase exposure