CVE-2023-31436
📋 TL;DR
This vulnerability in the Linux kernel's QFQ scheduler allows an out-of-bounds write due to improper bounds checking. Attackers with local access can potentially escalate privileges or crash the system. It affects Linux systems running kernel versions before 6.2.13.
💻 Affected Systems
- Linux kernel
📦 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 →⚠️ Risk & Real-World Impact
Worst Case
Local privilege escalation to root, kernel panic causing system crash, or arbitrary code execution in kernel context.
Likely Case
Local privilege escalation allowing attackers to gain root access on vulnerable systems.
If Mitigated
Limited impact if proper access controls prevent local user access or if SELinux/AppArmor restricts kernel interactions.
🎯 Exploit Status
Requires local access and knowledge of kernel exploitation techniques. No public exploit code identified in references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Linux kernel 6.2.13 and later
Vendor Advisory: https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.2.13
Restart Required: Yes
Instructions:
1. Update kernel to version 6.2.13 or later. 2. For distributions: Use package manager (apt/yum/dnf) to update kernel package. 3. Reboot system to load new kernel.
🔧 Temporary Workarounds
Disable QFQ scheduler
linuxRemove or disable QFQ scheduler module if not required
modprobe -r sch_qfq
echo 'blacklist sch_qfq' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Restrict local user access to systems
- Implement strict SELinux/AppArmor policies to limit kernel interactions
🔍 How to Verify
Check if Vulnerable:
Check kernel version: uname -r. If version is earlier than 6.2.13, system may be vulnerable.Check Version:
uname -rVerify Fix Applied:
After patching, verify kernel version is 6.2.13 or later with uname -r📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- Ooops messages in dmesg
- System crash reports
Network Indicators:
- None - local exploit only
SIEM Query:
Search for kernel panic events or privilege escalation attempts in system logs🔗 References
- http://packetstormsecurity.com/files/173087/Kernel-Live-Patch-Security-Notice-LSN-0095-1.html
- http://packetstormsecurity.com/files/173757/Kernel-Live-Patch-Security-Notice-LSN-0096-1.html
- http://packetstormsecurity.com/files/175963/Kernel-Live-Patch-Security-Notice-LSN-0099-1.html
- https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.2.13
- https://github.com/torvalds/linux/commit/3037933448f60f9acb705997eae62013ecb81e0d
- https://lists.debian.org/debian-lts-announce/2023/06/msg00008.html
- https://security.netapp.com/advisory/ntap-20230609-0001/
- https://www.debian.org/security/2023/dsa-5402
- https://www.spinics.net/lists/stable-commits/msg294885.html
- http://packetstormsecurity.com/files/173087/Kernel-Live-Patch-Security-Notice-LSN-0095-1.html
- http://packetstormsecurity.com/files/173757/Kernel-Live-Patch-Security-Notice-LSN-0096-1.html
- http://packetstormsecurity.com/files/175963/Kernel-Live-Patch-Security-Notice-LSN-0099-1.html
- https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.2.13
- https://github.com/torvalds/linux/commit/3037933448f60f9acb705997eae62013ecb81e0d
- https://lists.debian.org/debian-lts-announce/2023/06/msg00008.html
- https://security.netapp.com/advisory/ntap-20230609-0001/
- https://www.debian.org/security/2023/dsa-5402
- https://www.spinics.net/lists/stable-commits/msg294885.html
