CVE intelligence

CVE-2026-63875

Vulnerability intelligence

Published Jul 19, 2026Sources checked Oct 8, 2026

7.8HIGHCVSS out of 10

What this means

Review the available evidence

CVE-2026-63875 and is rated High severity with a CVSS score of 7.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.2%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-63875?

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

arm64: tlb: Flush walk cache when unsharing PMD tables

When huge_pmd_unshare() is called to unshare a PMD table, the tlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true but the aarch64 tlb_flush() only checked tlb->freed_tables to determine whether to use TLBF_NONE (vae1is, invalidates walk cache) or TLBF_NOWALKCACHE (vale1is, leaf-only).

This caused the stale PMD page table entry to remain in the walk cache after unshare, potentially leading to incorrect page table walks.

Fix by including unshared_tables in the check, so that when unsharing tables, TLBF_NONE is used and the walk cache is properly invalidated.

Here is the detailed distinction between vae1is and vale1is:

| Instruction Combination | Actual Invalidation Scope | | ------------------------ | --------------------------------------------------| | `VAE1IS` + TTL=`0` | All entries at all levels (full invalidation) | | `VAE1IS` + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2 | | `VALE1IS` + TTL=`0` | Leaf entries at all levels (non-leaf not cleared) | | `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only |

Source: NVD