Linux Kernel Vulnerability in MMC Core Affecting Multiple Distributions

CVE-2026-43484

What is CVE-2026-43484?

A vulnerability in the Linux kernel's MMC core was identified that involved improper handling of control flags. The design allowed simultaneous updates to the claimed and retune flags within a shared bitfield, leading to potential race conditions. When multiple contexts attempted to modify these flags concurrently, unexpected behavior could occur, specifically causing spurious warnings related to the claimed state of the MMC host. To mitigate this, modifications were made to redefine the relevant flags as boolean values, thus eliminating shared-word dependencies and ensuring safer, more reliable flag management.

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