CVE-2023-1583 – A NULL pointer dereference vulnerability in the... (How to Fix)

Q: What is the severity of CVE-2023-1583?

CVE-2023-1583 has a CVSS score of 5.5 (MEDIUM). A NULL pointer dereference vulnerability in the Linux kernel's io_uring subsystem allows unprivileged local users to trigger a system crash (kernel panic). This affects Linux systems with io_uring enabled, potentially impacting servers, workstations, and containers.

📋 TL;DR

A NULL pointer dereference vulnerability in the Linux kernel's io_uring subsystem allows unprivileged local users to trigger a system crash (kernel panic). This affects Linux systems with io_uring enabled, potentially impacting servers, workstations, and containers.

💻 Affected Systems

Products:

Linux Kernel

Versions: Linux kernel versions from introduction of io_uring feature up to fixes in 6.3+

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Requires io_uring subsystem to be enabled and accessible to users. Most modern Linux distributions have io_uring enabled by default.

📦 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...

Learn more about Linux Kernel →

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...

Learn more about Linux Kernel →

⚠️ Risk & Real-World Impact

🔴

Worst Case

System-wide kernel panic leading to complete denial of service, requiring physical or remote console access to reboot.

🟠

Likely Case

Local unprivileged user causes targeted system crash, disrupting services on affected host.

🟢

If Mitigated

With proper access controls, only authorized users could trigger the crash, reducing exposure.

🌐 Internet-Facing: LOW - Requires local access to exploit, not remotely exploitable.

🏢 Internal Only: MEDIUM - Any local user account (including compromised ones) can cause denial of service.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ✅ No

Complexity: LOW

Exploit requires local user access but no special privileges. The vulnerability is straightforward to trigger once understood.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Linux kernel 6.3+ with specific commits: 02a4d923e4400a36d340ea12d8058f69ebf3a383 and 761efd55a0227aca3a69deacdaa112fffd44fe37

Vendor Advisory: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=02a4d923e4400a36d340ea12d8058f69ebf3a383

Restart Required: Yes

Instructions:

1. Update Linux kernel to version 6.3 or later. 2. For older kernels, backport the specific commits. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable io_uring for unprivileged users

linux

Restrict access to io_uring system calls using seccomp or other security mechanisms

sysctl -w kernel.io_uring_disabled=1

Use user namespace restrictions

linux

Isolate users in containers with restricted capabilities

docker run --cap-drop=ALL --security-opt=no-new-privileges image_name

🧯 If You Can't Patch

Implement strict access controls to limit local user accounts
Monitor for crash events and investigate any kernel panic occurrences

🔍 How to Verify

Check if Vulnerable:

Check kernel version and if io_uring is enabled: uname -r && grep io_uring /proc/kallsyms

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version is 6.3+ or contains the fix commits: uname -r && git log --oneline | grep -E '02a4d923e4400a36d340ea12d8058f69ebf3a383|761efd55a0227aca3a69deacdaa112fffd44fe37'

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages in /var/log/kern.log or dmesg
System crash/reboot events
io_uring related error messages

Network Indicators:

None - local exploit only

SIEM Query:

source="kern.log" AND "kernel panic" OR "NULL pointer dereference" OR "io_uring"

📊 Metadata

CVE ID: CVE-2023-1583

CVSS v3 Score: 5.5 (MEDIUM)

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

CWE: CWE-476

Published: March 24, 2023

Last Updated: February 20, 2025

🔗 References

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🔗 Related Vulnerabilities

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