Linux Kernel up to 6.18.29/7.0.6/7.1-rc2 x86 kernel_fpu_begin memory corruption

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.18.29/7.0.6/7.1-rc2 and classified as critical. This impacts the function kernel_fpu_begin of the component x86. Executing a manipulation can lead to memory corruption. This vulnerability appears as CVE-2026-46290. There is no available exploit. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.29/7.0.6/7.1-rc2. It has been declared as critical. This vulnerability affects the function kernel_fpu_begin of the component x86. The manipulation with an unknown input leads to a memory corruption vulnerability. The CWE definition for the vulnerability is CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: x86/efi: Fix graceful fault handling after FPU softirq changes Since commit d02198550423 ("x86/fpu: Improve crypto performance by making kernel-mode FPU reliably usable in softirqs"), kernel_fpu_begin() calls fpregs_lock() which uses local_bh_disable() instead of the previous preempt_disable(). This sets SOFTIRQ_OFFSET in preempt_count during the entire EFI runtime service call, causing in_interrupt() to return true in normal task context. The graceful page fault handler efi_crash_gracefully_on_page_fault() uses in_interrupt() to bail out for faults in real interrupt context. With SOFTIRQ_OFFSET now set, the handler always bails out, leaving EFI firmware page faults unhandled. This escalates to die() which also sees in_interrupt() as true and calls panic("Fatal exception in interrupt"), resulting in a hard system freeze. On systems with buggy firmware that triggers page faults during EFI runtime calls (e.g., accessing unmapped memory in GetTime()), this causes an unrecoverable hang instead of the expected graceful EFI_ABORTED recovery. Fix by replacing in_interrupt() with !in_task(). This preserves the original intent of bailing for interrupts or NMI faults, while no longer falsely triggering from the FPU code path's local_bh_disable(). [ardb: Sashiko spotted that using 'in_hardirq() || in_nmi()' leaves a window where a softirq may be taken before fpregs_lock() is called, but after efi_rts_work.efi_rts_id has been assigned, and any page faults occurring in that window will then be misidentified as having been caused by the firmware. Instead, use !in_task(), which incorporates in_serving_softirq(). ]

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-46290 since 05/13/2026. The exploitation appears to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 06/08/2026).

Upgrading to version 6.18.30, 7.0.7 or 7.1-rc3 eliminates this vulnerability. Applying the patch 22b365ba1af3d8c6036b8e5112fffe80998b85a0/db155b86d1523e85941f61efd7d7ffb594cc9a29/088f65e206087bf903743bd18417261d7a4c9644 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.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 7.0.0
• 7.0.1
• 7.0.2
• 7.0.3
• 7.0.4
• 7.0.5
• 7.0.6
• 7.1-rc1
• 7.1-rc2

License

• open-source

Website

• Vendor: https://www.kernel.org/

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CPE 2.2info

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Entryinfo

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