CVE-2025-38000
📋 TL;DR
A race condition in the Linux kernel's HFSC (Hierarchical Fair Service Curve) queuing discipline can cause inconsistent queue accounting when packets are enqueued. This may lead to use-after-free conditions, potentially causing kernel crashes or privilege escalation. Affects Linux systems using HFSC queuing.
💻 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 →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 panic leading to system crash, or potential privilege escalation to root via use-after-free exploitation.
Likely Case
System instability, packet loss, or kernel crashes under specific network conditions.
If Mitigated
Minimal impact if HFSC is not used or with proper kernel hardening features enabled.
🎯 Exploit Status
Exploitation requires specific network conditions and HFSC configuration. Race condition makes reliable exploitation challenging.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions containing commits: 1034e3310752e8675e313f7271b348914008719a, 3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335, 3f981138109f63232a5fb7165938d4c945cc1b9d, 49b21795b8e5654a7df3d910a12e1060da4c04cf, 89c301e929a0db14ebd94b4d97764ce1d6981653
Vendor Advisory: https://git.kernel.org/stable/c/1034e3310752e8675e313f7271b348914008719a
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable HFSC queuing
linuxRemove or disable HFSC (sch_hfsc) queuing discipline configuration
tc qdisc del dev <interface> root
Remove HFSC configurations from /etc/network/interfaces or network scripts
🧯 If You Can't Patch
- Disable HFSC queuing discipline on all network interfaces
- Implement network segmentation to limit potential impact
🔍 How to Verify
Check if Vulnerable:
Check if HFSC is configured: tc qdisc show | grep hfscCheck Version:
uname -rVerify Fix Applied:
Check kernel version contains fix commits: uname -r and verify against patched versions📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- OOPs messages related to network scheduling
- System crashes during network operations
Network Indicators:
- Unexpected packet drops
- Network interface instability
SIEM Query:
kernel:panic OR kernel:Oops AND (hfsc OR sch_hfsc OR network_scheduling)🔗 References
- https://git.kernel.org/stable/c/1034e3310752e8675e313f7271b348914008719a
- https://git.kernel.org/stable/c/3f3a22eebbc32b4fa8ce9c1d5f9db214b45b9335
- https://git.kernel.org/stable/c/3f981138109f63232a5fb7165938d4c945cc1b9d
- https://git.kernel.org/stable/c/49b21795b8e5654a7df3d910a12e1060da4c04cf
- https://git.kernel.org/stable/c/89c301e929a0db14ebd94b4d97764ce1d6981653
- https://git.kernel.org/stable/c/93c276942e75de0e5bc91576300d292e968f5a02
- https://git.kernel.org/stable/c/f1dde3eb17dc1b8bd07aed00004b1e05fc87a3d4
- https://git.kernel.org/stable/c/f9f593e34d2fb67644372c8f7b033bdc622ad228
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
