CVE-2022-20422

What it actually does

Race condition in emulation_proc_handler of armv8_deprecated.c allows memory corruption in the kernel, enabling local privilege escalation without additional privileges or user interaction.

Why it matters to the business

Attackers with local access on affected Android devices or Debian systems can gain full control, leading to device or server compromise; the four-year-old issue affects a wide range of deployed systems with low but stable exploit likelihood.

How an attack unfolds

An attacker with local user access on an affected Android or Debian system triggers concurrent access to the emulation handler, races to corrupt kernel memory, and escalates privileges to root.

How to fix it

Apply upstream kernel patches that add proper synchronization around emulation_proc_handler; for Android, install the latest security patch level that includes the A-237540956 fix; for Debian, update to a kernel build that resolves the race.

How to confirm the fix worked

Confirm the running kernel contains the locking fix in armv8_deprecated.c; test that concurrent access to the emulation handler no longer produces memory corruption under load.

Typical attack path

1. Gain local shell or process execution on the target device
2. Trigger concurrent calls to emulation_proc_handler
3. Exploit resulting memory corruption to alter kernel data structures
4. Escalate to root-level privileges and persist

How to detect it

Review kernel logs and audit trails for repeated or anomalous calls involving armv8_deprecated emulation, unexpected privilege changes, or memory corruption panics on affected systems.

What your security team should do

• Immediately update all Android devices and Debian systems to patched kernels
• Restrict local user accounts and limit execution of untrusted code
• Monitor EPSS and threat intelligence for any future increase in exploitation