CVE-2023-52741 – A use-after-free vulnerability in the Linux ker... (How to Fix)

Q: What is the severity of CVE-2023-52741?

CVE-2023-52741 has a CVSS score of 7.8 (HIGH). A use-after-free vulnerability in the Linux kernel's CIFS/SMB client implementation allows attackers to potentially execute arbitrary code or cause system crashes when reading files from unstable network connections. This affects Linux systems using CIFS/SMB file sharing with vulnerable kernel versions. The vulnerability occurs in the rdata->read_into_pages() function during network reconnection scenarios.

📋 TL;DR

A use-after-free vulnerability in the Linux kernel's CIFS/SMB client implementation allows attackers to potentially execute arbitrary code or cause system crashes when reading files from unstable network connections. This affects Linux systems using CIFS/SMB file sharing with vulnerable kernel versions. The vulnerability occurs in the rdata->read_into_pages() function during network reconnection scenarios.

💻 Affected Systems

Products:

Linux kernel

Versions: Specific vulnerable kernel versions with CIFS/SMB support (check git commits for exact ranges)

Operating Systems: Linux distributions using vulnerable kernel versions

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using CIFS/SMB client functionality. Systems not mounting SMB shares are not vulnerable.

📦 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 →

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 →

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

Kernel memory corruption leading to arbitrary code execution with kernel privileges, system crashes, or data corruption.

🟠

Likely Case

System instability, kernel panics, or denial of service when accessing files over unstable network connections.

🟢

If Mitigated

Limited impact with proper network segmentation and restricted CIFS/SMB usage.

🌐 Internet-Facing: MEDIUM - Requires CIFS/SMB access to vulnerable systems from untrusted networks.

🏢 Internal Only: MEDIUM - Internal attackers with network access to CIFS/SMB shares could exploit this.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Exploitation requires ability to trigger network instability during CIFS/SMB file operations. No public exploits known at this time.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Kernel versions containing commits: 2b693fe3f760c87fd9768e759f6297f743a1b3b0, 3684a2f6affa1ca52a5d4a12f04d0652efdee65e, aa5465aeca3c66fecdf7efcf554aed79b4c4b211, d1fba1e096ffc7ec11df863a97c50203c47315b9

Vendor Advisory: https://git.kernel.org/stable/c/2b693fe3f760c87fd9768e759f6297f743a1b3b0

Restart Required: Yes

Instructions:

1. Update Linux kernel to patched version from your distribution vendor. 2. Reboot system to load new kernel. 3. Verify kernel version after reboot.

🔧 Temporary Workarounds

Disable CIFS/SMB client

linux

Prevent use of CIFS/SMB file sharing if not required

# Unmount any CIFS/SMB shares
umount -t cifs
# Blacklist cifs module
echo 'blacklist cifs' >> /etc/modprobe.d/blacklist-cifs.conf

Network segmentation

linux

Restrict CIFS/SMB traffic to trusted networks only

# Example iptables rule to restrict CIFS/SMB ports
iptables -A INPUT -p tcp --dport 445 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 445 -j DROP

🧯 If You Can't Patch

Avoid using CIFS/SMB file sharing on vulnerable systems
Implement strict network controls to prevent untrusted access to CIFS/SMB services

🔍 How to Verify

Check if Vulnerable:

Check kernel version and verify if CIFS module is loaded: 'lsmod | grep cifs' and 'uname -r'

Check Version:

uname -r

Verify Fix Applied:

Verify kernel version after update and check that CIFS module functions without crashes during network instability tests

📡 Detection & Monitoring

Log Indicators:

Kernel panic messages
KASAN use-after-free reports in dmesg
CIFS/SMB connection errors followed by crashes

Network Indicators:

Unusual CIFS/SMB traffic patterns during network instability
Multiple reconnection attempts to SMB shares

SIEM Query:

source="kernel" AND ("KASAN: use-after-free" OR "BUG: KASAN" OR "cifs_readv_receive" OR "readpages_fill_pages")

📊 Metadata

CVE ID: CVE-2023-52741

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-416

Published: May 21, 2024

Last Updated: January 6, 2025

🔗 References

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🔗 Related Vulnerabilities

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