CVE-2023-52656 – This CVE addresses dead code removal in the Lin... (How to Fix)

Q: What is the severity of CVE-2023-52656?

CVE-2023-52656 has a CVSS score of 5.5 (MEDIUM). This CVE addresses dead code removal in the Linux kernel's io_uring subsystem related to SCM_RIGHTS file descriptor passing. The vulnerability itself was already mitigated by previous patches that removed the vulnerable functionality, but residual code remained. Systems running affected Linux kernel versions with io_uring enabled are potentially impacted.

📋 TL;DR

This CVE addresses dead code removal in the Linux kernel's io_uring subsystem related to SCM_RIGHTS file descriptor passing. The vulnerability itself was already mitigated by previous patches that removed the vulnerable functionality, but residual code remained. Systems running affected Linux kernel versions with io_uring enabled are potentially impacted.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific versions between when SCM_RIGHTS support was added to io_uring and when it was removed (exact range depends on distribution backports)

Operating Systems: Linux distributions using affected kernel versions

Default Config Vulnerable: ✅ No

Notes: Only affects systems with io_uring enabled (default in most modern kernels). The actual vulnerable code was already disabled in earlier patches.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

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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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 →

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 →

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

Potential memory corruption or use-after-free leading to kernel panic or privilege escalation if the dead code could be triggered.

🟠

Likely Case

Low impact since the vulnerable functionality was already removed; this patch cleans up residual code.

🟢

If Mitigated

Minimal to no impact as the actual vulnerability was addressed in earlier patches.

🌐 Internet-Facing: LOW - Requires local access or specific io_uring usage patterns.

🏢 Internal Only: LOW - Requires local user access and specific kernel configurations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: NO

Unauthenticated Exploit: ✅ No

Complexity: HIGH

This is a code cleanup patch for functionality already removed. No active exploitation expected.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 6e5e6d274956, 6fc19b3d8a45, 88c49d9c8961, a3812a47a320, a6771f343af9

Vendor Advisory: https://git.kernel.org/stable/c/6e5e6d274956305f1fc0340522b38f5f5be74bdb

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution. 2. For custom kernels: apply the referenced git commits. 3. Reboot system to load new kernel.

🔧 Temporary Workarounds

Disable io_uring (not recommended)

linux

Disable io_uring subsystem via kernel boot parameters

Add 'io_uring.disabled=1' to kernel command line in GRUB or bootloader

🧯 If You Can't Patch

Implement strict access controls to limit local user privileges
Monitor system logs for unusual io_uring related activity

🔍 How to Verify

Check if Vulnerable:

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

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version includes the fix commits: 'uname -r' and check with distribution's security advisories

📡 Detection & Monitoring

Log Indicators:

Kernel oops or panic messages related to io_uring
System crash dumps mentioning SCM_RIGHTS

Network Indicators:

None - local vulnerability only

SIEM Query:

source="kernel" AND ("io_uring" OR "SCM_RIGHTS") AND ("panic" OR "oops" OR "BUG")

📊 Metadata

CVE ID: CVE-2023-52656

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

Published: May 14, 2024

Last Updated: December 23, 2025

🔗 References

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