CVE-2026-53343 ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow
A kernel crash occurs during boot on specific ARM configurations due to an unaligned memory access in KASAN VMAP stack handling.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-53343?
CVE-2026-53343 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 Jul 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:
ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow
Commit 44e9a3bb76e5 ("ARM: 9430/1: entry: Do a dummy read from VMAP shadow") added a dummy read from the KASAN VMAP stack shadow in __switch_to(). The read uses ldr, but the KASAN shadow address is byte-granular and is not guaranteed to be word aligned.
ARMv5 faults unaligned word loads. With CONFIG_KASAN_VMALLOC and CONFIG_VMAP_STACK enabled, ARM926/VersatilePB crashes in __switch_to() with an alignment exception before reaching init.
Use ldrb for the dummy shadow access. The code only needs to fault in the shadow mapping if the stack shadow is missing, so a byte load is sufficient and matches the granularity of KASAN shadow memory.
Which versions are affected by CVE-2026-53343?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53343?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-53343 being exploited?
There is no known exploitation of CVE-2026-53343 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-53343, DEBIAN-CVE-2026-53343, GHSA-4f2p-2mpv-gjwq, ROOT-OS-UBUNTU-2404-CVE-2026-53343, UBUNTU-CVE-2026-53343.