CVE-2026-23402

Home/CVE/In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Only WARN in direct MMUs when overwri

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In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Only WARN in direct MMUs when overwri

In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Only WARN in direct MMUs when overwriting shadow-present SPTE Adjust KVM's sanity check against overwriting a shadow-present SPTE with a another SPTE with a different target PFN to only apply to direct MMUs, i.e. only to MMUs without shadowed gPTEs. While it's impossible for KVM to overwrite a shadow-present SPTE in response to a guest write, writes from outside the scope of KVM, e.g. from host userspace, aren't detected by KVM's write tracking and so can break KVM's shadow paging rules. ------------[ cut here ]------------ pfn != spte_to_pfn(*sptep) WARNING: arch/x86/kvm/mmu/mmu.c:3069 at mmu_set_spte+0x1e4/0x440 [kvm], CPU#0: vmx_ept_stale_r/872 Modules linked in: kvm_intel kvm irqbypass CPU: 0 UID: 1000 PID: 872 Comm: vmx_ept_stale_r Not tainted 7.0.0-rc2-eafebd2d2ab0-sink-vm #319 PREEMPT Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:mmu_set_spte+0x1e4/0x440 [kvm] Call Trace: <TASK> ept_page_fault+0x535/0x7f0 [kvm] kvm_mmu_do_page_fault+0xee/0x1f0 [kvm] kvm_mmu_page_fault+0x8d/0x620 [kvm] vmx_handle_exit+0x18c/0x5a0 [kvm_intel] kvm_arch_vcpu_ioctl_run+0xc55/0x1c20 [kvm] kvm_vcpu_ioctl+0x2d5/0x980 [kvm] __x64_sys_ioctl+0x8a/0xd0 do_syscall_64+0xb5/0x730 entry_SYSCALL_64_after_hwframe+0x4b/0x53 </TASK> ---[ end trace 0000000000000000 ]---.

MEDIUM · CVSS 5.5 EPSS 8e-05

EPSS exploitation odds0.01% · top 99%

Monitor

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

No Sigma yet — build one → YARA rules0

Look this up elsewhere - one-click external pivots

NVD CVE.org CISA 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-2026-23402, 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).

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Severity & exploitation scoring

View on NVD →

CVSS base score

5.5

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

EPSS exploitation probability

0.01%

Top 99%odds of exploitation in the next 30 days

CVSS metric silhouette

shape grows toward worst-case

CVSS vector breakdown

Exploitability - how they get in

Attack Vector

Network Adjacent Local Physical

Attack Complexity

Low High

Privileges Required

None Low High

User Interaction

None Required

Scope

Unchanged Changed

Impact - what breaks

Confidentiality

None Low High

Integrity

None Low High

Availability

None Low High

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

Lifecycle

01 Apr 2026Published to NVD
24 Apr 2026Last modified

Every entry is a recorded date - NVD publish/modify, CISA KEV add, public exploit disclosure. No inferred events.

View attack path from CVE-2026-23402

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ATT&CK techniques

Techniques this CVE enables - linked via CWE → CAPEC → ATT&CK. Pills with a solid outline are named directly in ATT&CK or Nuclei templates (high confidence); the others are linked through weakness mappings.

T1068 · Exploitation for Privilege Escalation

▤ Build a SIEM detection for these techniques

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Affected Products & Versions

linux kernel>= 6.16.1 and < 6.18.21
linux kernel>= 6.19 and < 6.19.11
linux kernelall versions

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Related CVEs

CVEs linked to this one by a shared weakness (CWE) or affected product - joins on data already in the engine, with the reason shown per row. Not a guess.

CVE-1999-1442 Bug in AMD K6 processor on Linux 2.0.x and 2.1.x kernels allows local users to c... same product CVE-1999-1285 Linux 2.1.132 and earlier allows local users to cause a denial of service (resou... same product CVE-1999-0656 The ugidd RPC interface, by design, allows remote attackers to enumerate valid u... same product CVE-1999-0431 Linux 2.2.3 and earlier allow a remote attacker to perform an IP fragmentation a... same product CVE-1999-1018 IPChains in Linux kernels 2.2.10 and earlier does not reassemble IP fragments be... same product CVE-1999-1341 Linux kernel before 2.3.18 or 2.2.13pre15, with SLIP and PPP options, allows loc... same product

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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/a1e0f7150639bc30a8e75476d1c7daab77d44992Patch

https://git.kernel.org/stable/c/bab090e8fd5607f77379ea78b9d0c683cb1538a9Patch

https://git.kernel.org/stable/c/df83746075778958954aa0460cca55f4b3fc9c02Patch