CVE-2022-50536
📋 TL;DR
A double-free vulnerability in the Linux kernel's BPF sockmap subsystem allows local attackers to cause a use-after-free condition. This can lead to kernel memory corruption, system crashes, or potential privilege escalation. Affects Linux systems with BPF sockmap functionality enabled.
💻 Affected Systems
- Linux Kernel
⚠️ Risk & Real-World Impact
Worst Case
Kernel panic leading to system crash or potential privilege escalation to root via kernel memory corruption.
Likely Case
System instability, kernel crashes, or denial of service on affected systems.
If Mitigated
Limited impact if BPF sockmap is not used or systems are patched.
🎯 Exploit Status
Requires local access and ability to trigger BPF sockmap operations. No public exploit code identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in stable kernel releases via commits referenced in CVE
Vendor Advisory: https://git.kernel.org/stable/c/113236e8f49f262f318c00ebb14b15f4834e87c1
Restart Required: Yes
Instructions:
1. Update Linux kernel to patched version. 2. Check distribution-specific security advisories. 3. Reboot system after kernel update.
🔧 Temporary Workarounds
Disable BPF sockmap
linuxDisable BPF sockmap functionality if not required
echo 0 > /proc/sys/net/core/bpf_jit_enable
Remove sockmap BPF programs if loaded
🧯 If You Can't Patch
- Restrict local user access to systems
- Monitor for kernel panic/crash events and investigate suspicious BPF activity
🔍 How to Verify
Check if Vulnerable:
Check kernel version and if BPF sockmap is enabled: uname -r and check /proc/sys/net/core/bpf_jit_enableCheck Version:
uname -rVerify Fix Applied:
Verify kernel version is updated beyond vulnerable commits and system is stable after applying BPF sockmap operations📡 Detection & Monitoring
Log Indicators:
- Kernel panic logs
- refcount_t warnings in kernel logs
- TCP socket state errors
Network Indicators:
- Unusual BPF program loading
- Suspicious local socket operations
SIEM Query:
source="kernel" AND ("refcount_t" OR "TCP socket in state" OR "use-after-free")🔗 References
- https://git.kernel.org/stable/c/113236e8f49f262f318c00ebb14b15f4834e87c1
- https://git.kernel.org/stable/c/28e4a763cd4a2b1a78852216ef4bd7df3a05cec6
- https://git.kernel.org/stable/c/578a7628b838a3ac8ad61deaab5a816ff032ac13
- https://git.kernel.org/stable/c/7508b9f4daac4ec7dfe0b6fb2d688b1c1c105e10
- https://git.kernel.org/stable/c/7a9841ca025275b5b0edfb0b618934abb6ceec15
- https://git.kernel.org/stable/c/8786bde11a4f31b63b3036731df0b47337a7a245
