Linux Kernel up to 6.19.8 lapic_resume initialization

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CTI Interest Score
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6.2$0-$5k0.00

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 6.19.8. This vulnerability affects the function lapic_resume. The manipulation leads to initialization. This vulnerability is traded as CVE-2026-43363. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.19.8. This issue affects the function lapic_resume. The manipulation with an unknown input leads to a initialization vulnerability. Using CWE to declare the problem leads to CWE-665. The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: x86/apic: Disable x2apic on resume if the kernel expects so When resuming from s2ram, firmware may re-enable x2apic mode, which may have been disabled by the kernel during boot either because it doesn't support IRQ remapping or for other reasons. This causes the kernel to continue using the xapic interface, while the hardware is in x2apic mode, which causes hangs. This happens on defconfig + bare metal + s2ram. Fix this in lapic_resume() by disabling x2apic if the kernel expects it to be disabled, i.e. when x2apic_mode = 0. The ACPI v6.6 spec, Section 16.3 [1] says firmware restores either the pre-sleep configuration or initial boot configuration for each CPU, including MSR state: When executing from the power-on reset vector as a result of waking from an S2 or S3 sleep state, the platform firmware performs only the hardware initialization required to restore the system to either the state the platform was in prior to the initial operating system boot, or to the pre-sleep configuration state. In multiprocessor systems, non-boot processors should be placed in the same state as prior to the initial operating system boot. (further ahead) If this is an S2 or S3 wake, then the platform runtime firmware restores minimum context of the system before jumping to the waking vector. This includes: CPU configuration. Platform runtime firmware restores the pre-sleep configuration or initial boot configuration of each CPU (MSR, MTRR, firmware update, SMBase, and so on). Interrupts must be disabled (for IA-32 processors, disabled by CLI instruction). (and other things) So at least as per the spec, re-enablement of x2apic by the firmware is allowed if "x2apic on" is a part of the initial boot configuration. [1] https://uefi.org/specs/ACPI/6.6/16_Waking_and_Sleeping.html#initialization [ bp: Massage. ]

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-43363 since 05/01/2026. The exploitation is known to be difficult. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/10/2026).

The vulnerability scanner Nessus provides a plugin with the ID 326222 (EulerOS 2.0 SP12 : kernel (EulerOS-SA-2026-2535)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.19 or 6.19.9 eliminates this vulnerability. Applying the patch a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c/3dd0812a7c764cd8f3b0182441ac22da0a7f3b09/965289b120cc68cca886c75219c68b8c15751d73/f591938072115bf08730b8530c67fab189cc6308/1a85f84214f9d790216547ac6086bf8033cd9e5a/11712c4eb384098db4cb08792e223c818b908c1a/1d8440c1e7c49715f937416ac90cf260f1f1712c/8cc7dd77a1466f0ec58c03478b2e735a5b289b96 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (326222) and CERT Bund (WID-SEC-2026-1454). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Red Hat Enterprise Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • Microsoft Azure Linux
  • Open Source Linux Kernel

Productinfo

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Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.2

VulDB Base Score: 7.1
VulDB Temp Score: 6.8
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Initialization
CWE: CWE-665
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 326222
Nessus Name: EulerOS 2.0 SP12 : kernel (EulerOS-SA-2026-2535)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.253/5.15.203/6.1.167/6.6.130/6.12.78/6.18.19/6.19.9
Patch: a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c/3dd0812a7c764cd8f3b0182441ac22da0a7f3b09/965289b120cc68cca886c75219c68b8c15751d73/f591938072115bf08730b8530c67fab189cc6308/1a85f84214f9d790216547ac6086bf8033cd9e5a/11712c4eb384098db4cb08792e223c818b908c1a/1d8440c1e7c49715f937416ac90cf260f1f1712c/8cc7dd77a1466f0ec58c03478b2e735a5b289b96

Timelineinfo

05/01/2026 CVE reserved
05/08/2026 +7 days Advisory disclosed
05/08/2026 +0 days VulDB entry created
07/10/2026 +63 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-43363 (🔒)
GCVE (CVE): GCVE-0-2026-43363
GCVE (VulDB): GCVE-100-362189
CERT Bund: WID-SEC-2026-1454 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/08/2026 18:19
Updated: 07/10/2026 13:19
Changes: 05/08/2026 18:19 (58), 05/18/2026 09:55 (11), 06/19/2026 07:27 (7), 07/10/2026 13:19 (2)
Complete: 🔍
Cache ID: 216::103

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