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CVE-2026-63875

HIGH severity · CVSS 7.8 · CWE-670
7.8CVSS HIGH

Summary

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 |

Impact & exploitability

Attack vectorLocal
Attack complexityLow
Privileges requiredLow
User interactionNone
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)0%

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products we track (1)

Linux Kernel

Recommendation

Apply the vendor fix promptly. Open any affected product above for its exact safe version.

Official patch: https://git.kernel.org/stable/c/0199c9d57861f17b556b6cba1f765c7cce79745b ↗

Additional information