CVE-2026-90212

What the bug is

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.

Where it lives

The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.

arch/arm64/kernel/efi.c

What this is

EXTENSIBLE FIRMWARE INTERFACE (EFI)MAINTAINERS section matched on arch/*/kernel/efi.c · linux-efi@vger.kernel.org · Maintained

Check it on the machine

grep -w CONFIG_EFI /boot/config-$(uname -r)

Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.

Show whether Debian builds this, per release

Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed.

• bookwormYnot built on ppc64el/powerpc64le
• trixieYnot built on armel/rpi, ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x
• forky, sidYnot built on ppc64el/powerpc64le, ppc64el/powerpc64le-64k, s390x/s390x

Y

built in where it is built at all; some flavours do not build it

Build switch

CONFIG_EFI

From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages

Signals

Published

2026-09-17 (31 days ago)source

CVSS

no vector published, unrated

Attack vector

not published

EPSS

0.20%, higher than 8.9% of all CVEssource

CISA KEV

not listedthe KEV catalogue

Debian urgency

unimportantsource

Subsystem

arch/arm64

Upstream fixes

The versions the CNA records as introducing and fixing this, and the commit for each. source

Introduced	Fixed in	Commit
6.19	7.2.6	829539c4a650
6.19	7.3	e98a9d014637