Linux Kernel up to 6.14-rc1 KVM_RUN null pointer dereference

Summaryinfo

A vulnerability marked as critical has been reported in Linux Kernel up to 6.14-rc1. This vulnerability affects the function KVM_RUN. The manipulation leads to null pointer dereference. This vulnerability is uniquely identified as CVE-2025-21740. No exploit exists. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.14-rc1 and classified as critical. This issue affects the function KVM_RUN. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Ensure NX huge page recovery thread is alive before waking When waking a VM's NX huge page recovery thread, ensure the thread is actually alive before trying to wake it. Now that the thread is spawned on-demand during KVM_RUN, a VM without a recovery thread is reachable via the related module params. BUG: kernel NULL pointer dereference, address: 0000000000000040 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 RIP: 0010:vhost_task_wake+0x5/0x10 Call Trace: set_nx_huge_pages+0xcc/0x1e0 [kvm] param_attr_store+0x8a/0xd0 module_attr_store+0x1a/0x30 kernfs_fop_write_iter+0x12f/0x1e0 vfs_write+0x233/0x3e0 ksys_write+0x60/0xd0 do_syscall_64+0x5b/0x160 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f3b52710104 Modules linked in: kvm_intel kvm CR2: 0000000000000040

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2025-21740 since 12/29/2024. The exploitation is known to be difficult. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.14-rc1 or 6.14-rc2 eliminates this vulnerability. Applying the patch 2b3928b7c896e5a9fb6b1373924adafe8e01a0c6/974f85f1f7eb7dc7fce0988046e06eeccab576a7/43fb96ae78551d7bfa4ecca956b258f085d67c40 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 vulnerability database at CERT Bund (WID-SEC-2025-0453). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• Siemens SIMATIC S7
• RESF Rocky Linux
• Dell NetWorker
• Dell Avamar
• Red Hat OpenShift
• IBM QRadar SIEM
• SolarWinds Security Event Manager
• Dell PowerProtect Data Domain
• Open Source Linux Kernel
• IBM DataPower Gateway
• Dell Secure Connect Gateway
• Dell PowerScale OneFS
• Dell ECS

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.14-rc1

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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