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CVE-2026-43363— x86/apic: Disable x2apic on resume if the kernel expects so

EPSS 0.02% · P7
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I. Basic Information for CVE-2026-43363

Vulnerability Information
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Vulnerability Title
x86/apic: Disable x2apic on resume if the kernel expects so
Source: NVD (National Vulnerability Database)
Vulnerability Description
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. ]
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于恢复时x2apic模式未按预期禁用，可能导致系统挂起。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
LinuxLinux 6e1cb38a2aef7680975e71f23de187859ee8b158 ~ a6ad6f2e31b524cbb66b2f370bad0cf17d327e6c -
LinuxLinux 2.6.28 -

II. Public POCs for CVE-2026-43363

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III. Intelligence Information for CVE-2026-43363

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Same Patch Batch · Linux · 2026-05-08 · 199 CVEs total

CVE-2026-433049.8 CRITICALlibceph: define and enforce CEPH_MAX_KEY_LEN
CVE-2026-433419.8 CRITICALnet/ipv6: ioam6: prevent schema length wraparound in trace fill
CVE-2026-433769.8 CRITICALksmbd: fix use-after-free by using call_rcu() for oplock_info
CVE-2026-433799.8 CRITICALksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()
CVE-2026-433849.8 CRITICALnet/tcp-ao: Fix MAC comparison to be constant-time
CVE-2026-434659.8 CRITICALnet/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
CVE-2026-434029.8 CRITICALkthread: consolidate kthread exit paths to prevent use-after-free
CVE-2026-434149.8 CRITICALscsi: qla2xxx: Completely fix fcport double free
CVE-2026-433839.4 CRITICALnet/tcp-md5: Fix MAC comparison to be constant-time
CVE-2026-434069.1 CRITICALlibceph: prevent potential out-of-bounds reads in process_message_header()
CVE-2026-434079.1 CRITICALlibceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()
CVE-2026-432848.8 HIGHxfrm: esp: avoid in-place decrypt on shared skb frags
CVE-2026-433228.8 HIGHBluetooth: hci_sync: Fix UAF in le_read_features_complete
CVE-2026-433348.8 HIGHBluetooth: SMP: force responder MITM requirements before building the pairing response
CVE-2026-433918.8 HIGHnsfs: tighten permission checks for handle opening
CVE-2026-434038.8 HIGHnsfs: tighten permission checks for ns iteration ioctls
CVE-2026-432918.3 HIGHnet: nfc: nci: Fix parameter validation for packet data
CVE-2026-433658.2 HIGHxfs: fix undersized l_iclog_roundoff values
CVE-2026-434668.2 HIGHnet/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery
CVE-2026-434528.2 HIGHnetfilter: x_tables: guard option walkers against 1-byte tail reads

Showing top 20 of 199 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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