# CVE-2026-68163: linux: In the Linux kernel, the following vulnerability has been resolved:  mm/page_vma_mapped: fix device-private PMD handl...

CVE-2026-68163 is fixed in linux on 1 platform by DEBIAN-CVE-2026-68163 (version 7.1.6-1), released August 11, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-68163
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 10, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:  mm/page_vma_mapped: fix device-private PMD handling  Commit 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries") introduced the concept of device-private PMD entries, but did not correctly update the rmap walk code to account for them.  As a result, when page_vma_mapped_walk() encounters device-private PMD entries, it takes no action other than to acquire the PMD lock and exit.  However this is highly problematic for two reasons - firstly, device private entries possess a PFN so check_pmd() needs to be called to ensure an overlapping PFN range.  Secondly, and more importantly, if PVMW_MIGRATION is set the caller assumes the returned entry is a migration entry, resulting in memory corruption when the caller tries to interpret the device private entry as such.  In addition, commit 146287290023 ("mm/huge_memory: implement device-private THP splitting") allowed device private PMDs to be split like THP mappings, but again did not update this code path.  As a result, we might race a PMD split prior to acquiring the PMD lock.  This patch addresses all of these issues by invoking check_pmd(), ensuring PMVW_MIGRATION is not set and checks whether a split raced us we do for PMD THP and migration entries.  Instead of checking for a subset of the cases after taking the pmd_lock(), put device-private along with pmd_trans_huge() and pmd_is_migration_entry().  Also remove thp_migration_supported() as it is already guarded by pmd_is_migration_entry().  [akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David]

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.1.6-1 | [DEBIAN-CVE-2026-68163](https://patchblox.com/security/data/fix/linux/debian-cve-2026-68163.md) | Aug 11, 2026 |

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Data as of 2026-11-09T07:25:28Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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