Medium 5.5Published Sep 19, 2025

CVE-2025-39845x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()

Updated under an hour ago (Oct 27, 2026, 12:40 AM ET)

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In the Linux kernel, the following vulnerability has been resolved: x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() Define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to ensure page tables are properly synchronized when calling p*d_populate_kernel(). For 5-level paging, synchronization is performed via pgd_populate_kernel(). In 4-level paging, pgd_populate() is a no-op, so synchronization is instead performed at the P4D level via p4d_populate_kernel(). This fixes intermittent boot failures on systems using 4-level paging and a large amount of persistent memory: BUG: unable to handle page fault for address: ffffe70000000034 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: 0002 [#1] SMP NOPTI RIP: 0010:__init_single_page+0x9/0x6d Call Trace: <TASK> __init_zone_device_page+0x17/0x5d memmap_init_zone_device+0x154/0x1bb pagemap_range+0x2e0/0x40f memremap_pages+0x10b/0x2f0 devm_memremap_pages+0x1e/0x60 dev_dax_probe+0xce/0x2ec [device_dax] dax_bus_probe+0x6d/0xc9 [... snip ...] </TASK> It also fixes a crash in vmemmap_set_pmd() caused by accessing vmemmap before sync_global_pgds() [1]: BUG: unable to handle page fault for address: ffffeb3ff1200000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 0 P4D 0 Oops: Oops: 0002 [#1] PREEMPT SMP NOPTI Tainted: [W]=WARN RIP: 0010:vmemmap_set_pmd+0xff/0x230 <TASK> vmemmap_populate_hugepages+0x176/0x180 vmemmap_populate+0x34/0x80 __populate_section_memmap+0x41/0x90 sparse_add_section+0x121/0x3e0 __add_pages+0xba/0x150 add_pages+0x1d/0x70 memremap_pages+0x3dc/0x810 devm_memremap_pages+0x1c/0x60 xe_devm_add+0x8b/0x100 [xe] xe_tile_init_noalloc+0x6a/0x70 [xe] xe_device_probe+0x48c/0x740 [xe] [... snip ...]

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: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 14, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 8d400913c231bd1da74067255816453f96cd35b0 before 744ff519c72de31344a627eaf9b24e9595aae554; 8d400913c231bd1da74067255816453f96cd35b0 builds before 5f761d40ee95d2624f839c90ebeef2d5c55007f5; from 8d400913c231bd1da74067255816453f96cd35b0 before 26ff568f390a531d1bd792e49f1a401849921960; from 8d400913c231bd1da74067255816453f96cd35b0 before b7f4051dd3388edd30e9a6077c05c486aa31e0d4; 8d400913c231bd1da74067255816453f96cd35b0 builds before 6bf9473727569e8283c1e2445c7ac42cf4fc9fa9; from 8d400913c231bd1da74067255816453f96cd35b0 before 6659d027998083fbb6d42a165b0c90dc2e8ba989	CNA record
Siemens SIMATIC CN 4100 siemens:simatic_cn_4100 (from the name)	before V5.0	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 5.13 before 5.15.192; from 5.16 before 6.1.151; from 6.2 before 6.6.105; from 6.7 before 6.12.46; from 6.13 before 6.16.6; 6.17; 6.17; 6.17; and 1 more ranges	NVD
debian debian_linux debian:debian_linux	11.0	NVD

References

References

https://git.kernel.org/stable/c/744ff519c72de31344a627eaf9b24e9595aae554	patch
https://git.kernel.org/stable/c/5f761d40ee95d2624f839c90ebeef2d5c55007f5	patch
https://git.kernel.org/stable/c/26ff568f390a531d1bd792e49f1a401849921960	patch
https://git.kernel.org/stable/c/b7f4051dd3388edd30e9a6077c05c486aa31e0d4	patch
https://git.kernel.org/stable/c/6bf9473727569e8283c1e2445c7ac42cf4fc9fa9	patch
https://git.kernel.org/stable/c/6659d027998083fbb6d42a165b0c90dc2e8ba989	patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html	mailing-list, third-party-advisory
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-032379.html
https://cert-portal.siemens.com/productcert/html/ssa-457936.html

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.