CVE-2022-1786 – A use-after-free vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2022-1786?

CVE-2022-1786 has a CVSS score of 7.8 (HIGH). A use-after-free vulnerability in the Linux kernel's io_uring subsystem allows local attackers to crash the system or potentially escalate privileges. This affects Linux systems with specific io_uring configurations. Only local users with access to create io_uring instances are affected.

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's io_uring subsystem allows local attackers to crash the system or potentially escalate privileges. This affects Linux systems with specific io_uring configurations. Only local users with access to create io_uring instances are affected.

💻 Affected Systems

Products:

Linux kernel

Versions: Linux kernel versions from introduction of io_uring IOPOLL feature (around 5.6) to patched versions

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when io_uring is configured with IORING_SETUP_IOPOLL flag and multiple tasks complete submissions on the same ring.

📦 What is this software?

Linux Kernel by Linux

The Linux Kernel is the core component of the Linux operating system, serving as the critical interface between computer hardware and software processes. As the heart of millions of servers, cloud infrastructure, embedded systems, Android devices, and IoT deployments worldwide, the Linux Kernel mana...

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⚠️ Risk & Real-World Impact

🔴

Worst Case

Local privilege escalation to root, complete system compromise, or kernel panic causing system crash.

🟠

Likely Case

Kernel crash leading to denial of service and potential data loss from unsaved work.

🟢

If Mitigated

Limited impact if proper access controls prevent local users from creating io_uring instances.

🌐 Internet-Facing: LOW - Requires local access to exploit, not directly exploitable over network.

🏢 Internal Only: HIGH - Any local user with ability to create io_uring instances can potentially exploit this.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploit requires local access and knowledge of io_uring subsystem. Proof-of-concept code has been published in security advisories.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel 5.18.1 and later, backported to various distribution kernels

Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=2087760

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. For RHEL/CentOS: yum update kernel. 3. For Ubuntu/Debian: apt update && apt upgrade linux-image. 4. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable io_uring IOPOLL feature

linux

Prevent creation of io_uring instances with IORING_SETUP_IOPOLL flag

sysctl -w kernel.io_uring_disabled=2

Restrict io_uring system calls

linux

Use seccomp or other mechanisms to block io_uring related system calls

🧯 If You Can't Patch

Implement strict access controls to prevent local users from creating io_uring instances
Monitor for io_uring creation attempts and kernel panic/crash events

🔍 How to Verify

Check if Vulnerable:

Check kernel version: uname -r and compare with patched versions from your distribution's security advisory

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version after update and reboot, check that io_uring functions normally without crashes

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
System crash/reboot events
io_uring related error messages in dmesg

Network Indicators:

None - local exploit only

SIEM Query:

search 'kernel panic' OR 'system crashed' OR 'io_uring' in system logs

📊 Metadata

CVE ID: CVE-2022-1786

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-843

Published: June 2, 2022

Last Updated: November 21, 2024

🔗 References

https://bugzilla.redhat.com/show_bug.cgi?id=2087760 Issue Tracking,Third Party Advisory
https://security.netapp.com/advisory/ntap-20220722-0001/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5161 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2087760 Issue Tracking,Third Party Advisory
https://security.netapp.com/advisory/ntap-20220722-0001/ Third Party Advisory
https://www.debian.org/security/2022/dsa-5161 Third Party Advisory

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🔗 Related Vulnerabilities

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