CVE-2026-90212 arm64/efi: Avoid voluntary preemption with efi_mm installed
A race condition in Linux kernel EFI runtime services on ARM64 with software PAN enabled can cause kernel memory corruption and crashes.
- 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-2026-90212?
CVE-2026-90212 is a memory corruption vulnerability in Linux, published on 17 Sep 2026. 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:
arm64/efi: Avoid voluntary preemption with efi_mm installed
Gus reports a bad kernel memory access when using software PAN (CONFIG_ARM64_SW_TTBR0_PAN=y) on a machine with support for EFI runtime services:
Unable to handle kernel access to user memory outside uaccess routines at virtual address 00000000f322ff30 Mem abort info: ESR = 0x0000000096000004 FSC = 0x04: level 0 translation fault Internal error: Oops: 0000000096000004 [#1] SMP Workqueue: efi_rts_wq efi_call_rts pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : efi_call_rts+0xd8/0x288 Call trace: efi_call_rts+0xd8/0x288 (P) process_one_work+0x178/0x4f8 worker_thread+0x194/0x328
This is because the fpsimd context management code called from __efi_fpsimd_begin() can preempt voluntarily, returning later to the EFI code with an incorrect value for TTBR0_EL1 thanks to the deferred mm switching used by the software PAN implementation.
Since EFI runtime services cannot preempt voluntarily and because the fpsimd switching code does not rely on the TTBR0_EL1 mappings, simply reorder the fpsimd switch so that it occurs before we change the page-table.
Which versions are affected by CVE-2026-90212?
How do I fix CVE-2026-90212?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-90212 being exploited?
There is no known exploitation of CVE-2026-90212 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-90212, GHSA-mvqq-j4gg-mmgx, UBUNTU-CVE-2026-90212.