CVE-2025-40149
📋 TL;DR
This CVE describes a use-after-free vulnerability in the Linux kernel's TLS implementation. When setsockopt() is called, get_netdev_for_sock() could access freed memory, potentially leading to kernel crashes or privilege escalation. This affects Linux systems with TLS kernel module enabled.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash, or potential privilege escalation allowing attackers to gain root access.
Likely Case
Kernel crash causing denial of service, potentially requiring system reboot.
If Mitigated
No impact if patched or TLS kernel module not loaded.
🎯 Exploit Status
Requires local access or ability to make socket system calls. Exploitation would require triggering the specific code path.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel trees (commits referenced in CVE)
Vendor Advisory: https://git.kernel.org/stable/c/13159c7125636371543a82cb7bbae00ab36730cc
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the fix. 2. Check with your distribution vendor for specific patched kernel version. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable TLS kernel module
linuxUnload the TLS kernel module if not required
modprobe -r tls
Blacklist TLS module
linuxPrevent TLS module from loading at boot
echo 'blacklist tls' >> /etc/modprobe.d/blacklist.conf
🧯 If You Can't Patch
- Restrict user access to systems to minimize attack surface
- Implement strict process isolation and containerization
🔍 How to Verify
Check if Vulnerable:
Check if TLS module is loaded: lsmod | grep tlsCheck Version:
uname -rVerify Fix Applied:
Check kernel version against patched versions from distribution vendor📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- OOM killer activity related to kernel memory
Network Indicators:
- Unusual socket operations from unexpected processes
SIEM Query:
Process monitoring for setsockopt() calls with TLS sockets🔗 References
- https://git.kernel.org/stable/c/13159c7125636371543a82cb7bbae00ab36730cc
- https://git.kernel.org/stable/c/2b1bef126bbb8d0da51491357559126d567c1dee
- https://git.kernel.org/stable/c/c65f27b9c3be2269918e1cbad6d8884741f835c5
- https://git.kernel.org/stable/c/e37ca0092ddace60833790b4ad7a390408fb1be9
- https://git.kernel.org/stable/c/f09cd209359a23f88d4f3fa3d2379d057027e53c
- https://git.kernel.org/stable/c/feb474ddbf26b51f462ae2e60a12013bdcfc5407
