CVE-2026-43363

System hang via mismatched APIC resume mode

Published May 8, 2026 · Updated May 8, 2026

Denial of service in the Linux kernel allows local users to hang bare-metal x86 systems during suspend-to-RAM resume. During lapic_resume(), the kernel leaves x2APIC enabled by firmware while continuing to use the xAPIC interface when x2apic_mode is zero. The failure requires bare metal, a default kernel configuration, firmware that restores x2APIC, and an S2 or S3 resume; the resulting hang interrupts system availability.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the Linux kernel allows local users to hang bare-metal x86 systems during suspend-to-RAM resume. During lapic_resume(), the kernel leaves x2APIC enabled by firmware while continuing to use the xAPIC interface when x2apic_mode is zero. The failure requires bare metal, a default kernel configuration, firmware that restores x2APIC, and an S2 or S3 resume; the resulting hang interrupts system availability.

The record

CVE
CVE-2026-43363
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.28
  2. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <11712c4eb384098db4cb08792e223c818b908c1a
  3. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <1a85f84214f9d790216547ac6086bf8033cd9e5a
  4. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <1d8440c1e7c49715f937416ac90cf260f1f1712c
  5. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <3dd0812a7c764cd8f3b0182441ac22da0a7f3b09
  6. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <8cc7dd77a1466f0ec58c03478b2e735a5b289b96
  7. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <965289b120cc68cca886c75219c68b8c15751d73
  8. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c
  9. Affected versionversion=6e1cb38a2aef7680975e71f23de187859ee8b158 <f591938072115bf08730b8530c67fab189cc6308

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.28; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <11712c4eb384098db4cb08792e223c818b908c1a; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <1a85f84214f9d790216547ac6086bf8033cd9e5a; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <1d8440c1e7c49715f937416ac90cf260f1f1712c; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <3dd0812a7c764cd8f3b0182441ac22da0a7f3b09; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <8cc7dd77a1466f0ec58c03478b2e735a5b289b96; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <965289b120cc68cca886c75219c68b8c15751d73; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c; version=6e1cb38a2aef7680975e71f23de187859ee8b158 <f591938072115bf08730b8530c67fab189cc6308

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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