Publication Date: July 1, 2025
Overview: Urgent Security Fixes for Linux Kernel (FIPS)
Multiple high-severity security vulnerabilities have been discovered in the Linux kernel (FIPS), posing risks of denial-of-service (DoS) attacks, arbitrary code execution, and system compromise.
This security advisory (USN-7607-2) details the affected subsystems, patch instructions, and mitigation strategies.
🔴 Key Threats Addressed:
Use-after-free vulnerability in the Bluetooth stack (CVE-2022-3640)
Exploitable flaws in SCSI, NFS, NILFS2, memory management, and USB sound devices
Potential privilege escalation and kernel panic risks
⚠️ Immediate Action Required: A system reboot is mandatory after patching. Third-party kernel modules must be recompiled due to an unavoidable ABI change.
Affected Linux Kernel Packages & Versions
The following Ubuntu FIPS-certified kernel packages require urgent updates:
| Ubuntu Release | Package Version |
|---|---|
| 16.04 (Xenial) | linux-image-4.4.0-1115-fips – 4.4.0-1115.122 |
| 16.04 (Xenial) | linux-image-fips – 4.4.0.1115.116 |
📌 Extended Security Coverage:
Ubuntu Pro offers 10-year security maintenance for 25,000+ packages (free for up to 5 machines).
Reduce exposure by upgrading to a supported kernel version.
Detailed Vulnerability Analysis
1. Critical Bluetooth Stack Exploit (CVE-2022-3640)
A use-after-free flaw allows local attackers to trigger:
System crashes (DoS)
Arbitrary code execution with elevated privileges
2. Additional High-Risk Vulnerabilities
| CVE ID | Affected Subsystem | Risk Level |
|---|---|---|
| CVE-2025-37932 | SCSI subsystem | Critical |
| CVE-2025-37798 | NFS client | High |
| CVE-2024-53197 | NILFS2 file system | Medium-High |
| CVE-2024-50116 | Memory management | High |
| CVE-2024-46787 | Network traffic control | Medium |
🔍 Why This Matters: Unpatched systems are vulnerable to privilege escalation, data corruption, and remote attacks.
Step-by-Step Patch Instructions
Run a standard system update:
sudo apt update && sudo apt upgrade
Reboot immediately to apply kernel changes.
Recompile third-party modules (if applicable).
🚨 Important Note: If you manually removed standard kernel metapackages (e.g., linux-generic), reinstall them before updating.
How to Mitigate Future Risks
✅ Enable Ubuntu Pro for extended security patches.
✅ Monitor kernel updates via Ubuntu Security Notices (USN).
✅ Isolate critical systems from untrusted networks.
FAQ: Linux Kernel Security Patches
Q: Can these vulnerabilities be exploited remotely?
A: Most require local access, but some network-related flaws (e.g., NFS) could be abused remotely.
Q: Is a reboot always necessary after a kernel update?
A: Yes—kernel patches only take effect after a reboot.
Q: How do I check my current kernel version?
A: Run:
uname -r
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