CVE-2025-22077
📋 TL;DR
This CVE describes a Linux kernel vulnerability in the SMB client where a reverted fix incorrectly revived kernel TCP sockets without proper network namespace references. This can cause TCP socket leaks and potential use-after-free conditions when network namespaces are destroyed. Systems running affected Linux kernel versions with CIFS/SMB client functionality are at risk.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic or system crash due to use-after-free when network namespace cleanup interacts with orphaned TCP sockets, potentially leading to denial of service.
Likely Case
TCP socket resource exhaustion leading to connection failures and degraded network performance for CIFS/SMB connections.
If Mitigated
Minimal impact if systems don't use CIFS/SMB client functionality or have proper network namespace isolation.
🎯 Exploit Status
Exploitation requires specific conditions: CIFS/SMB client usage, network namespace operations, and TCP connection state transitions. No public exploits known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Kernel versions with reverting commits: 4b6f6bf1bde8d6045c389fda8d21c304dfe49384, 8dbf060480236877703bff0106fc984576184d11, 95d2b9f693ff2a1180a23d7d59acc0c4e72f4c41, f761eeefd531e6550cd3a5c047835b4892acb00d
Vendor Advisory: https://git.kernel.org/stable/c/4b6f6bf1bde8d6045c389fda8d21c304dfe49384
Restart Required: Yes
Instructions:
1. Update Linux kernel to version containing the reverting commits. 2. Check with your distribution vendor for specific patched kernel versions. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable CIFS/SMB client
linuxPrevent vulnerability by disabling CIFS/SMB client functionality if not needed
modprobe -r cifs
echo 'blacklist cifs' >> /etc/modprobe.d/blacklist.conf
Reduce TCP orphan sockets
linuxLower tcp_max_orphans to limit potential socket leaks
sysctl -w net.ipv4.tcp_max_orphans=16384
echo 'net.ipv4.tcp_max_orphans=16384' >> /etc/sysctl.conf
🧯 If You Can't Patch
- Avoid using CIFS/SMB client mounts and connections
- Implement network namespace isolation and avoid destroying namespaces with active CIFS connections
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if it contains the problematic commit: 'uname -r' and check with distribution vendorCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated to one containing the reverting commits. Check CIFS module is functioning normally.📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs mentioning use-after-free
- TCP socket exhaustion warnings in dmesg
- CIFS connection failures
Network Indicators:
- Increased TCP sockets in FIN_WAIT_1 state
- CIFS/SMB connection timeouts
SIEM Query:
source="kernel" AND ("use-after-free" OR "TCP" OR "CIFS" OR "SMB")