# CVE-2026-53343: ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow

CVE-2026-53343 is fixed in linux on 1 platform, first by DEBIAN-CVE-2026-53343, released July 2, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-53343
- Priority: High
- CVSS: 7.1 (Important)
- EPSS: 0.0013
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 1, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-53343

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.176-1 | [DEBIAN-CVE-2026-53343](https://patchblox.com/security/data/fix/linux/debian-cve-2026-53343.md) | Jul 2, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.94-1 | [DEBIAN-CVE-2026-53343](https://patchblox.com/security/data/fix/linux/debian-cve-2026-53343.md) | Jul 2, 2026 |
| Linux | linux Debian 14 | 7.0.13-1 | [DEBIAN-CVE-2026-53343](https://patchblox.com/security/data/fix/linux/debian-cve-2026-53343.md) | Jul 2, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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