---
id: CVE-2026-43484
title: 'mmc: core: Avoid bitfield RMW for claim/retune flags'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  mmc: core: Avoid bitfield RMW for claim/retune flags

  Move claimed and retune control flags out of the bitfield word to
  avoid unrelated RMW side effects in asynchronous…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 <
    41dce4dae583a8ce06a7ebf4ce704c46a142957c
  - >-
    Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 <
    bb7fc2498c3bb25fa6a91f22f4760005325cfbd5
  - >-
    Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 <
    270277c2ab631044867adb1bd2f2433d3892de6e
  - >-
    Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 <
    45038e03f15e992c48603fff8c6b1c9be5397ac9
  - >-
    Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 <
    0e06cc511c61cff1591e5435a207759adcc76b6d
  - >-
    Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 <
    d3a3caf44c8ec26f5d63dc17c1c7242effa60ebc
  - >-
    Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 <
    901084c51a0a8fb42a3f37d2e9c62083c495f824
  - Linux 4.15
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T15:40:59.499561Z'
published: '2026-05-13'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T15:42:57.242Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43484'
references:
  - url: 'https://git.kernel.org/stable/c/41dce4dae583a8ce06a7ebf4ce704c46a142957c'
  - url: 'https://git.kernel.org/stable/c/bb7fc2498c3bb25fa6a91f22f4760005325cfbd5'
  - url: 'https://git.kernel.org/stable/c/270277c2ab631044867adb1bd2f2433d3892de6e'
  - url: 'https://git.kernel.org/stable/c/45038e03f15e992c48603fff8c6b1c9be5397ac9'
  - url: 'https://git.kernel.org/stable/c/0e06cc511c61cff1591e5435a207759adcc76b6d'
  - url: 'https://git.kernel.org/stable/c/d3a3caf44c8ec26f5d63dc17c1c7242effa60ebc'
  - url: 'https://git.kernel.org/stable/c/901084c51a0a8fb42a3f37d2e9c62083c495f824'
tags:
  - cve.org
epss: 0.00114
epssPercentile: 0.01498
ingestedAt: '2026-11-06T15:54:03.899Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

mmc: core: Avoid bitfield RMW for claim/retune flags

Move claimed and retune control flags out of the bitfield word to
avoid unrelated RMW side effects in asynchronous contexts.

The host->claimed bit shared a word with retune flags. Writes to claimed
in __mmc_claim_host() or retune_now in mmc_mq_queue_rq() can overwrite
other bits when concurrent updates happen in other contexts, triggering
spurious WARN_ON(!host->claimed). Convert claimed, can_retune,
retune_now and retune_paused to bool to remove shared-word coupling.

## Affected

- `Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 < 41dce4dae583a8ce06a7ebf4ce704c46a142957c`
- `Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 < bb7fc2498c3bb25fa6a91f22f4760005325cfbd5`
- `Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 < 270277c2ab631044867adb1bd2f2433d3892de6e`
- `Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 < 45038e03f15e992c48603fff8c6b1c9be5397ac9`
- `Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 < 0e06cc511c61cff1591e5435a207759adcc76b6d`
- `Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 < d3a3caf44c8ec26f5d63dc17c1c7242effa60ebc`
- `Linux >= 6c0cedd1ef9527ef13e66875746570e76a3188a7 < 901084c51a0a8fb42a3f37d2e9c62083c495f824`
- `Linux 4.15`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.