CVE-2026-31600

/// Technical description

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

arm64: mm: Handle invalid large leaf mappings correctly

It has been possible for a long time to mark ptes in the linear map as

invalid. This is done for secretmem, kfence, realm dma memory un/share,

and others, by simply clearing the PTE_VALID bit. But until commit

a166563e7ec37 ("arm64: mm: support large block mapping when

rodata=full") large leaf mappings were never made invalid in this way.

It turns out various parts of the code base are not equipped to handle

invalid large leaf mappings (in the way they are currently encoded) and

I've observed a kernel panic while booting a realm guest on a

BBML2_NOABORT system as a result:

[ 15.432706] software IO TLB: Memory encryption is active and system is using DMA bounce buffers

[ 15.476896] Unable to handle kernel paging request at virtual address ffff000019600000

[ 15.513762] Mem abort info:

[ 15.527245] ESR = 0x0000000096000046

[ 15.548553] EC = 0x25: DA

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References