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CVE-2026-53343
ARM: 9475/1: entry: use byte load for KASAN VMAP stack shadow
Published 2026-07-01 (4 months ago) by the Linux kernel CNA. Subsystem arch/arm. Debian urgency: not yet assigned.
What to do, per Debian release
Debian's own status for CVE-2026-53343 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixedDLA-4665-1 · 2026-07-03 · text | 6.1.176-1 | Update the kernel and reboot. DLA-4665-1 shipped the fix on 2026-07-03, in 6.1.176-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
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 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/arm/kernel/entry-armv.S
- What this is
- ARM PORTMAINTAINERS section matched on arch/arm/ · linux-arm-kernel@lists.infradead.org · Odd Fixes
Show whether Debian builds this, per release
Debian builds this code. Every release below compiles the affected file into the kernels it ships.
- bookworm, trixie, forky, sidy
- y
- built into the kernel image on every flavour - only a patch removes it
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 Debian linux-config packages
Signals
- Published
- 2026-07-01 (4 months ago)source
- CVSS
- no vector published, unrated
- Attack vector
- not published
- EPSS
- 0.12%, higher than 2.0% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- arch/arm
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.1.120 | 6.1.176 | c0b8c148a775 |
| 6.6.64 | 6.6.143 | c2e3aadc8fef |
| 6.12.4 | 6.12.94 | c74990828d3c |
| 6.13 | 6.18.36 | 517720913bd3 |
| 6.13 | 7.0.13 | 2a4dc9a0ac33 |
| 6.13 | 7.1 | 77a1f6883dc6 |
Debian advisories
| Advisory | Date | Shipped to | Debian |
|---|---|---|---|
| DLA-4671-1 | 2026-07-05 | bullseye 6.1.176-1~deb11u1 | tracker |
| DLA-4665-1 | 2026-07-03 | bookworm 6.1.176-1 | tracker |
Why the CNA scored it this way
The kernel CNA published no CVSS vector and no reasoning for CVE-2026-53343, which is why it is shown as unrated rather than given an invented score. 6,405 of the 20,413 CVEs here carry reasoning; this is not one of them.