CVE-2026-43486

MEDIUM EPSS 1.7%
Published May 13, 20261mo ago · Modified Jun 26, 20263d ago
5.5 CVSS 3.1
Medium
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Published May 13, 2026 1mo ago
Last Modified Jun 26, 2026 3d ago

Description

In the Linux kernel, the following vulnerability has been resolved: arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults contpte_ptep_set_access_flags() compared the gathered ptep_get() value against the requested entry to detect no-ops. ptep_get() ORs AF/dirty from all sub-PTEs in the CONT block, so a dirty sibling can make the target appear already-dirty. When the gathered value matches entry, the function returns 0 even though the target sub-PTE still has PTE_RDONLY set in hardware. For a CPU with FEAT_HAFDBS this gathered view is fine, since hardware may set AF/dirty on any sub-PTE and CPU TLB behavior is effectively gathered across the CONT range. But page-table walkers that evaluate each descriptor individually (e.g. a CPU without DBM support, or an SMMU without HTTU, or with HA/HD disabled in CD.TCR) can keep faulting on the unchanged target sub-PTE, causing an infinite fault loop. Gathering can therefore cause false no-ops when only a sibling has been updated: - write faults: target still has PTE_RDONLY (needs PTE_RDONLY cleared) - read faults: target still lacks PTE_AF Fix by checking each sub-PTE against the requested AF/dirty/write state (the same bits consumed by __ptep_set_access_flags()), using raw per-PTE values rather than the gathered ptep_get() view, before returning no-op. Keep using the raw target PTE for the write-bit unfold decision. Per Arm ARM (DDI 0487) D8.7.1 ("The Contiguous bit"), any sub-PTE in a CONT range may become the effective cached translation and software must maintain consistent attributes across the range.

CVSS Details

Base Score
5.5
Exploitability
1.8
Impact
3.6
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack Vector Local
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
1.7% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-835

Affected Products 5

VendorProductVersionRange
linuxlinux_kernel*≥6.9  –  <6.12.78
linuxlinux_kernel*≥6.13  –  <6.18.19
linuxlinux_kernel*≥6.19  –  <6.19.9
linuxlinux_kernel7.0any
linuxlinux_kernel7.0any

References 4

  • git.kernel.org https://git.kernel.org/stable/c/05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/09d620555e59768776090073a2c59d2bc8506eb3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/6f92a7a8b48a523f910ef25dd83808710724f59b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/97c5550b763171dbef61e6239cab372b9f9cd4a2
    Patch

Remediation

  • git.kernel.org https://git.kernel.org/stable/c/05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/09d620555e59768776090073a2c59d2bc8506eb3
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/6f92a7a8b48a523f910ef25dd83808710724f59b
    Patch
  • git.kernel.org https://git.kernel.org/stable/c/97c5550b763171dbef61e6239cab372b9f9cd4a2
    Patch