CVE-2022-50720 x86/apic: Don't disable x2APIC if locked
Local attackers can exploit APIC MMIO interface to extract data from SGX enclaves if x2APIC is not locked by BIOS.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2022-50720?
CVE-2022-50720 is a vulnerability in Linux, published on 24 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
x86/apic: Don't disable x2APIC if locked
The APIC supports two modes, legacy APIC (or xAPIC), and Extended APIC (or x2APIC). X2APIC mode is mostly compatible with legacy APIC, but it disables the memory-mapped APIC interface in favor of one that uses MSRs. The APIC mode is controlled by the EXT bit in the APIC MSR.
The MMIO/xAPIC interface has some problems, most notably the APIC LEAK [1]. This bug allows an attacker to use the APIC MMIO interface to extract data from the SGX enclave.
Introduce support for a new feature that will allow the BIOS to lock the APIC in x2APIC mode. If the APIC is locked in x2APIC mode and the kernel tries to disable the APIC or revert to legacy APIC mode a GP fault will occur.
Introduce support for a new MSR (IA32_XAPIC_DISABLE_STATUS) and handle the new locked mode when the LEGACY_XAPIC_DISABLED bit is set by preventing the kernel from trying to disable the x2APIC.
On platforms with the IA32_XAPIC_DISABLE_STATUS MSR, if SGX or TDX are enabled the LEGACY_XAPIC_DISABLED will be set by the BIOS. If legacy APIC is required, then it SGX and TDX need to be disabled in the BIOS.
[1]: https://aepicleak.com/aepicleak.pdf
Which versions are affected by CVE-2022-50720?
How do I fix CVE-2022-50720?
Apply the vendor's patch.
Is CVE-2022-50720 being exploited?
There is no known exploitation of CVE-2022-50720 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2022-50720, GHSA-pc73-7j79-5x2x, ROOT-OS-DEBIAN-11-CVE-2022-50720, ROOT-OS-UBUNTU-2204-CVE-2022-50720, UBUNTU-CVE-2022-50720.