CVE-2020-14351

What it actually does

Use-after-free memory corruption in the Linux kernel perf subsystem that permits a local attacker with perf event monitoring rights to corrupt kernel memory and escalate privileges to root.

Why it matters to the business

A compromised local account can gain full system control, leading to data theft, ransomware deployment, or persistent unauthorized access across Linux servers and workstations.

How an attack unfolds

An attacker with local access and permission to monitor perf events triggers a race condition that frees a kernel object while it is still referenced, then reuses the dangling pointer to overwrite kernel structures and execute arbitrary code with elevated privileges.

How to fix it

Upgrade the Linux kernel to a version containing the fix for CVE-2020-14351; apply the latest vendor kernel packages for Red Hat Enterprise Linux or Debian; restrict unprivileged perf access via sysctl kernel.perf_event_paranoid=3 where full functionality is not required.

How to confirm the fix worked

Verify running kernel version is newer than the vulnerable release listed in vendor advisories; attempt to reproduce the original reproducer under a non-privileged account and confirm it no longer succeeds; review kernel changelog for perf subsystem fixes merged after 2020-12-03.

Typical attack path

1. Obtain local shell on target system
2. Confirm ability to open perf events (CAP_PERFMON or root-equivalent)
3. Trigger the use-after-free via crafted perf monitoring calls
4. Leverage memory corruption to overwrite kernel function pointers or credentials
5. Escalate to root and establish persistence or exfiltrate data

How to detect it

Review audit logs for unusual perf_event_open calls by non-administrative users followed by unexpected process privilege changes; examine kernel crash dumps or dmesg for use-after-free warnings in the perf subsystem; correlate with EDR telemetry showing local escalation after perf activity.

What your security team should do

• Immediately patch all affected Linux systems to the latest vendor kernel
• Reduce attack surface by setting kernel.perf_event_paranoid=3 on systems where perf is not needed by unprivileged users
• Monitor for new local privilege-escalation attempts via auditd or EDR rules targeting perf syscalls