CVE-2023-53439
📋 TL;DR
This Linux kernel vulnerability allows attackers to trigger a kernel warning (WARNING) by setting the skb->transport_header to the magic value 0xFFFF, which is reserved to indicate an unset transport header. This affects Linux systems with vulnerable kernel versions, primarily those using network packet processing. The issue was discovered through fuzzing and could potentially lead to denial of service.
💻 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 →⚠️ Risk & Real-World Impact
Worst Case
Kernel panic or system crash leading to denial of service, though the vulnerability only triggers a warning in the reported case.
Likely Case
Kernel warning messages in logs and potential performance degradation from repeated warnings, but no direct code execution.
If Mitigated
Minor logging noise with no operational impact if warnings are suppressed or monitored.
🎯 Exploit Status
Exploitation requires sending specially crafted network packets to trigger the condition; reported by syzbot fuzzer, indicating it's detectable but not widely exploited.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patches available in stable kernel commits: 3e785c8deb046305c61b9fa02265d0cb900c4a45, 424f8416bb39936df6365442d651ee729b283460, 70a76d6816148819d0464f71aafa126c84826628
Vendor Advisory: https://git.kernel.org/stable/c/3e785c8deb046305c61b9fa02265d0cb900c4a45
Restart Required: Yes
Instructions:
1. Identify current kernel version. 2. Update to a patched kernel version from your Linux distribution's repository. 3. Reboot the system to load the new kernel.
🔧 Temporary Workarounds
No effective workaround
allThis is a kernel-level bug in networking code; no configuration changes or workarounds are available to mitigate without patching.
🧯 If You Can't Patch
- Monitor system logs for kernel warnings related to skb_transport_header or virtio_net_hdr_to_skb to detect potential exploitation attempts.
- Restrict network access to vulnerable systems to reduce attack surface, though this may not be practical for all environments.
🔍 How to Verify
Check if Vulnerable:
Check kernel version against patched releases from your distribution; if unpatched and in affected version range, assume vulnerable.Check Version:
uname -rVerify Fix Applied:
After updating kernel, verify the new version is running and check that the specific commit hashes (e.g., 3e785c8deb046305c61b9fa02265d0cb900c4a45) are included in your kernel's changelog.📡 Detection & Monitoring
Log Indicators:
- Kernel warning messages containing 'skb_transport_header', 'virtio_net_hdr_to_skb', or similar terms in /var/log/kern.log or dmesg output.
Network Indicators:
- Unusual network packets targeting the packet_snd or virtio_net functions, though difficult to detect without deep packet inspection.
SIEM Query:
source="kern.log" AND "WARNING" AND ("skb_transport_header" OR "virtio_net_hdr_to_skb")