Medium 5.5Published May 13, 2026

CVE-2026-43486arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults

Updated under an hour ago (Oct 27, 2026, 11:00 PM ET)

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Exploited in the last 30 days

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: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: May 13, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	4602e5757bcceb231c3a13c36c373ad4a750eddb builds before 05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0; 4602e5757bcceb231c3a13c36c373ad4a750eddb builds before 6f92a7a8b48a523f910ef25dd83808710724f59b; 4602e5757bcceb231c3a13c36c373ad4a750eddb builds before 09d620555e59768776090073a2c59d2bc8506eb3; 4602e5757bcceb231c3a13c36c373ad4a750eddb builds before 97c5550b763171dbef61e6239cab372b9f9cd4a2	CNA record
linux linux_kernel linux:linux_kernel	from 6.9 before 6.12.78; from 6.13 before 6.18.19; from 6.19 before 6.19.9; 7.0; 7.0	NVD

References

References

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

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.