CVE-2026-31456

Home/CVE/In the Linux kernel, the following vulnerability has been resolved: mm/pagewalk: fix race between concurrent split and

CVE

In the Linux kernel, the following vulnerability has been resolved: mm/pagewalk: fix race between concurrent split and

In the Linux kernel, the following vulnerability has been resolved: mm/pagewalk: fix race between concurrent split and refault The splitting of a PUD entry in walk_pud_range() can race with a concurrent thread refaulting the PUD leaf entry causing it to try walking a PMD range that has disappeared. An example and reproduction of this is to try reading numa_maps of a process while VFIO-PCI is setting up DMA (specifically the vfio_pin_pages_remote call) on a large BAR for that process. This will trigger a kernel BUG: vfio-pci 0000:03:00.0: enabling device (0000 - 0002) BUG: unable to handle page fault for address: ffffa23980000000 PGD 0 P4D 0 Oops: 0000 [#1] SMP NOPTI ...

RIP: 0010:walk_pgd_range+0x3b5/0x7a0 Code: 8d 43 ff 48 89 44 24 28 4d 89 ce 4d 8d a7 00 20 00 48 8b 4c 24 28 49 81 e4 00 e0 ff 49 8d 44 24 ff 48 39 c8 4c 0f 43 e3 <49> f7 06 9f ff 75 3b 48 8b 44 24 20 48 8b 40 28 48 85 c0 74 RSP: 0018:ffffac23e1ecf808 EFLAGS: 00010287 RAX: 00007f44c01fffff RBX: 00007f4500000000 RCX: 00007f44ffffffff RDX: 0000000000000000 RSI: 000ffffffffff000 RDI: ffffffff93378fe0 RBP: ffffac23e1ecf918 R08: 0000000000000004 R09: ffffa23980000000 R10: 0000000000000020 R11: 0000000000000004 R12: 00007f44c0200000 R13: 00007f44c0000000 R14: ffffa23980000000 R15: 00007f44c0000000 FS: 00007fe884739580(0000) GS:ffff9b7d7a9c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffa23980000000 CR3: 000000c0650e2005 CR4: 0000000000770ef0 PKRU: 55555554 Call Trace: <TASK> __walk_page_range+0x195/0x1b0 walk_page_vma+0x62/0xc0 show_numa_map+0x12b/0x3b0 seq_read_iter+0x297/0x440 seq_read+0x11d/0x140 vfs_read+0xc2/0x340 ksys_read+0x5f/0xe0 do_syscall_64+0x68/0x130 ? get_page_from_freelist+0x5c2/0x17e0 ? mas_store_prealloc+0x17e/0x360 ? vma_set_page_prot+0x4c/0xa0 ? __alloc_pages_noprof+0x14e/0x2d0 ? __mod_memcg_lruvec_state+0x8d/0x140 ? __lruvec_stat_mod_folio+0x76/0xb0 ? __folio_mod_stat+0x26/0x80 ? do_anonymous_page+0x705/0x900 ? __handle_mm_fault+0xa8d/0x1000 ? __count_memcg_events+0x53/0xf0 ? handle_mm_fault+0xa5/0x360 ? do_user_addr_fault+0x342/0x640 ? arch_exit_to_user_mode_prepare.constprop.0+0x16/0xa0 ? irqentry_exit_to_user_mode+0x24/0x100 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7fe88464f47e Code: c0 e9 b6 fe ff 50 48 8d 3d be 07 0b 00 e8 69 01 02 00 66 0f 1f 84 00 64 8b 04 25 18 00 85 c0 75 14 0f 05 <48> 3d 00 f0 ff 77 5a c3 66 0f 1f 84 00 48 83 ec 28 RSP: 002b:00007ffe6cd9a9b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007fe88464f47e RDX: 0000000000020000 RSI: 00007fe884543000 RDI: 0000000000000003 RBP: 00007fe884543000 R08: 00007fe884542010 R09: 0000000000000000 R10: fffffffffffffbc5 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000 </TASK> Fix this by validating the PUD entry in walk_pmd_range() using a stable snapshot (pudp_get()). If the PUD is not present or is a leaf, retry the walk via ACTION_AGAIN instead of descending further. This mirrors the retry logic in walk_pte_range(), which lets walk_pmd_range() retry if the PTE is not being got by pte_offset_map_lock().

MEDIUM · CVSS 4.7 EPSS 0.00014

Monitor

No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence

Sigma rules0 YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA Vulners Exploit-DB GitHub PoC VulnCheck KEV GreyNoise

▸ How to read a CVE - triage first, then detect and patch

This page is every public fact about CVE-2026-31456, cross-linked. Its job is to answer one question fast - does this need my attention now? - and then hand you the two things you do about it. Here is how an analyst reads it.

Triage: should I act now? Four signals, and they are not interchangeable:

CVSSseverity - how bad it is IF exploited, 0-10. A high CVSS alone is not urgency; a flaw can be a perfect 10 and never actually be attacked. EPSSprobability - a model’s estimate of the chance it is exploited in the next 30 days, 0-1. This is the “will it actually happen” signal. CISA KEVconfirmed - it is being exploited in the wild right now. The strongest signal on the page; KEV beats any score. Weaponisedavailability - public exploits / PoCs, and especially Metasploit modules rated Excellent / Great. Reliable, packaged exploit code means low-skill attackers can use it today.

How they combine: KEV, or a dependable Metasploit module, means patch now regardless of CVSS. High CVSS + low EPSS + no exploit is real but not an emergency - schedule it. Low CVSS but KEV-listed still gets patched now. The verdict above already weighed these for you; this is how it got there.

Then what - two workflows:

Detectwhen you cannot patch today, follow this CVE to the ATT&CK techniques it enables, then Build a SIEM detection (the green button) - author a rule, test it in Atomic, deploy it. That buys visibility while the patch waits. PatchAffected products / packages tell you if you are exposed; Fixed versions by distribution and Vendor advisories give the exact version that closes it.

Reading order for the panels below: verdict + badges, then Public exploits / Metasploit (is it weaponised), then ATT&CK techniques + Sigma / IDS rules (can I detect it), then Affected products / packages + Fixed versions (am I exposed, what patches it), then Threat actors / IOCs (who uses it), then Scoring & timeline / references (the evidence).

View attack path from CVE-2026-31456

◆

ATT&CK techniques

Techniques this CVE enables - linked via CWECAPECATT&CK. High◆ = named directly in ATT&CK or Nuclei templates.

T1068 · Exploitation for Privilege Escalation

▤ Build a SIEM detection for these techniques

▤

CAPEC attack patterns

Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.

CAPEC-CAPEC-26 · Leveraging Race Conditions CAPEC-CAPEC-29 · Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions

⬡

Weakness Classification

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

▤

Affected Products & Versions

linux kernel>= 6.12 and < 6.18.21
linux kernel>= 6.19 and < 6.19.11
linux kernelall versions

📦

Fixed versions by distribution

The package version that resolves this CVE on each Linux distribution, from the vendor’s published security data. fixed in shows a patched version exists; open means the package is listed as affected with no fix yet.
suse sle15cluster-md-kmp-default open
suse sle15dlm-kmp-default open
suse sle15gfs2-kmp-default open
suse sle15kernel-default open
suse sle15kernel-default-base open
suse sle15kernel-default-devel open
suse sle15kernel-default-extra open
suse sle15kernel-default-livepatch open
suse sle15kernel-default-livepatch-devel open
suse sle15kernel-default-man open
suse sle15kernel-devel open
suse sle15kernel-devel-rt open
suse sle15kernel-macros open
suse sle15kernel-source open
suse sle15kernel-source-rt open
suse sle15ocfs2-kmp-default open
suse sle15reiserfs-kmp-default open

▣

Scoring & Timeline

4.7

MEDIUM · CVSS v3.1 · 416baaa9-dc9f-4396-8d5f-8c081fb06d67

View on NVD

Attack Vector

Network Adjacent Local Physical

Attack Complexity

Low High

Privileges Required

None Low High

User Interaction

None Required

Scope

Unchanged Changed

Confidentiality

None Low High

Integrity

None Low High

Availability

None Low High

Published to NVD22 Apr 2026 · 02:16 PM

CVSS VectorCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

⚑

Vendor Advisories

suse-csafopenSUSE-SU-2026:20826-1
suse-csafSUSE-SU-2026:21841-1
suse-csafSUSE-SU-2026:21845-1
suse-csafSUSE-SU-2026:21860-1

🔗

References & Sources

Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.

https://git.kernel.org/stable/c/38ec58670a0c5fc1edabdeccd857e586b7b3f318Patch

https://git.kernel.org/stable/c/3b89863c3fa482912911cd65a12a3aeef662c250Patch

https://git.kernel.org/stable/c/9bbbebd94dd5be25ec8c899d46ef01b33d5d22c0Patch