CVE-2025-39698
📋 TL;DR
A use-after-free vulnerability in the Linux kernel's io_uring futex subsystem allows local attackers to potentially cause kernel memory corruption or system crashes. This affects Linux systems with io_uring enabled and requires local access to exploit.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to denial of service, or potential privilege escalation if combined with other vulnerabilities
Likely Case
System instability, kernel crashes, or denial of service on affected systems
If Mitigated
Minimal impact with proper access controls and kernel hardening
🎯 Exploit Status
Requires local access and knowledge of kernel internals to exploit effectively
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel trees (commits: 508c1314b342b78591f51c4b5dadee31a88335df, d34c04152df517c59979b4bf2a47f491e06d3256, d9f93172820a53ab42c4b0e5e65291f4f9d00ad2)
Vendor Advisory: https://git.kernel.org/stable/c/508c1314b342b78591f51c4b5dadee31a88335df
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version from distribution vendor 2. Reboot system to load new kernel 3. Verify kernel version after reboot
🔧 Temporary Workarounds
Disable io_uring futex operations
LinuxPrevent use of vulnerable io_uring futex functionality
echo 0 > /proc/sys/kernel/io_uring/futex_enabled
🧯 If You Can't Patch
- Restrict local user access to systems with vulnerable kernels
- Implement kernel hardening measures like SELinux/AppArmor to limit damage potential
🔍 How to Verify
Check if Vulnerable:
Check kernel version and compare with patched versions from distribution vendorCheck Version:
uname -rVerify Fix Applied:
Verify kernel version matches patched version and test io_uring futex functionality📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- System crash dumps
- io_uring related error messages in dmesg
Network Indicators:
- None - local vulnerability only
SIEM Query:
search 'kernel panic' OR 'system crash' OR 'io_uring' in system logs