# 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.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-90212, GHSA-mvqq-j4gg-mmgx, UBUNTU-CVE-2026-90212

## 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.

## Is CVE-2026-90212 being exploited?

There is no known exploitation of CVE-2026-90212 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90212 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-90212 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-90212/ (Markdown: https://insights.sbomify.com/CVE-2026-90212/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90212
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90212
- OSV: https://osv.dev/vulnerability/CVE-2026-90212

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90212/
Summaries are generated and may contain mistakes; the official description above is the record.