High 8.8Published Oct 9, 2025

CVE-2025-39961iommu/amd/pgtbl: Fix possible race while increase page table level

Updated under an hour ago (Oct 28, 2026, 6:40 AM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: iommu/amd/pgtbl: Fix possible race while increase page table level The AMD IOMMU host page table implementation supports dynamic page table levels (up to 6 levels), starting with a 3-level configuration that expands based on IOVA address. The kernel maintains a root pointer and current page table level to enable proper page table walks in alloc_pte()/fetch_pte() operations. The IOMMU IOVA allocator initially starts with 32-bit address and onces its exhuasted it switches to 64-bit address (max address is determined based on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU driver increases page table level. But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads pgtable->[root/mode] without lock. So its possible that in exteme corner case, when increase_address_space() is updating pgtable->[root/mode], fetch_pte() reads wrong page table level (pgtable->mode). It does compare the value with level encoded in page table and returns NULL. This will result is iommu_unmap ops to fail and upper layer may retry/log WARN_ON. CPU 0 CPU 1 ------ ------ map pages unmap pages alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte() pgtable->root = pte (new root value) READ pgtable->[mode/root] Reads new root, old mode Updates mode (pgtable->mode += 1) Since Page table level updates are infrequent and already synchronized with a spinlock, implement seqcount to enable lock-free read operations on the read path.

CVSS: 8.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/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 15, 2026
First seen by InfoSec Signals: Oct 15, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	754265bcab78a9014f0f99cd35e0d610fcd7dfa7 builds before 075abf0b1a958acfbea2435003d228e738e90346; from 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 before cd92c8ab336c3a633d46e6f35ebcd3509ae7db3b; 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 builds before 7d462bdecb7d9c32934dab44aaeb7ea7d73a27a2; 754265bcab78a9014f0f99cd35e0d610fcd7dfa7 builds before 1e56310b40fd2e7e0b9493da9ff488af145bdd0c; 6fb92f18555a7b8e085267d513612dc0ff9a5360; b15bf74405faa1a65025eb8a6eb337e140e5250a; 0d50f7b1e8c80a8c20db5049e269468c059b0378; 785ca708a908b9c596ede852470ba28b8dc3e40b; and 4 more ranges	CNA record
linux linux_kernel linux:linux_kernel	from 4.9.194 before 4.10; from 4.14.146 before 4.15; from 4.19.75 before 4.20; from 5.2.17 before 5.3; from 5.3.1 before 6.6.108; from 6.7 before 6.12.49; from 6.13 before 6.16.9; 5.3; and 7 more ranges	NVD

References

References

https://git.kernel.org/stable/c/075abf0b1a958acfbea2435003d228e738e90346	patch
https://git.kernel.org/stable/c/cd92c8ab336c3a633d46e6f35ebcd3509ae7db3b	patch
https://git.kernel.org/stable/c/7d462bdecb7d9c32934dab44aaeb7ea7d73a27a2	patch
https://git.kernel.org/stable/c/1e56310b40fd2e7e0b9493da9ff488af145bdd0c	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.