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

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于contpte_ptep_set_access_flags函数在检测无操作时使用聚合值，可能导致SMMU或ATS故障时无限循环。

AI Predicted 5.3 Difficulty: Hard EPSS 0.16% · P5

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux 4602e5757bcceb231c3a13c36c373ad4a750eddb< 05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0 affected
4602e5757bcceb231c3a13c36c373ad4a750eddb< 6f92a7a8b48a523f910ef25dd83808710724f59b affected
4602e5757bcceb231c3a13c36c373ad4a750eddb< 09d620555e59768776090073a2c59d2bc8506eb3 affected
4602e5757bcceb231c3a13c36c373ad4a750eddb< 97c5550b763171dbef61e6239cab372b9f9cd4a2 affected
6.9 affected
< 6.9 unaffected
6.12.78≤ 6.12.* unaffected
6.18.19≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-43486

Vulnerability Information
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Vulnerability Title
arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于contpte_ptep_set_access_flags函数在检测无操作时使用聚合值，可能导致SMMU或ATS故障时无限循环。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 4602e5757bcceb231c3a13c36c373ad4a750eddb ~ 05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0 -
Linux Linux 6.9 -

II. Public POCs for CVE-2026-43486

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III. Intelligence Information for CVE-2026-43486

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Patches & Fixes for CVE-2026-43486 (4)

Same Patch Batch · Linux · 2026-05-13 · 14 CVEs total

CVE-2026-43481 7.8 HIGH net-shapers: don't free reply skb after genlmsg_reply()
CVE-2026-43476 7.8 HIGH iio: chemical: sps30_i2c: fix buffer size in sps30_i2c_read_meas()
CVE-2026-43489 liveupdate: luo_file: remember retrieve() status
CVE-2026-43487 ata: libata-core: Disable LPM on ST1000DM010-2EP102
CVE-2026-43488 usb: xhci: Prevent interrupt storm on host controller error (HCE)
CVE-2026-43485 nouveau/gsp: drop WARN_ON in ACPI probes
CVE-2026-43484 mmc: core: Avoid bitfield RMW for claim/retune flags
CVE-2026-43482 sched_ext: Disable preemption between scx_claim_exit() and kicking helper work
CVE-2026-43483 KVM: SVM: Set/clear CR8 write interception when AVIC is (de)activated
CVE-2026-43480 ASoC: amd: acp3x-rt5682-max9836: Add missing error check for clock acquisition
CVE-2026-43479 net: usb: lan78xx: fix WARN in __netif_napi_del_locked on disconnect
CVE-2026-43477 drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL
CVE-2026-43478 ASoC: codecs: rt1011: Use component to get the dapm context in spk_mode_put

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43486

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