CVE-2025-21740

KVM: x86/mmu: Ensure NX huge page recovery thread is alive before waking

Severity Score

5.5

*CVSS v3

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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: <TASK> 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 </TASK> Modules linked in: kvm_intel kvm CR2: 0000000000000040

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: <TASK> 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 </TASK> Modules linked in: kvm_intel kvm CR2: 0000000000000040

*Credits: N/A

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

None

Integrity

None

Availability

Complete

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2024-12-29 CVE Reserved
2025-02-27 CVE Published
2025-02-27 CVE Updated
2025-02-27 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CAPEC

References (4)

URL	Tag	Source
https://git.kernel.org/stable/c/931656b9e2ff7029aee0b36e17780621948a6ac1	Vuln. Introduced

URL	Date	SRC

URL	Date	SRC
https://git.kernel.org/stable/c/43fb96ae78551d7bfa4ecca956b258f085d67c40	2025-02-04
https://git.kernel.org/stable/c/2b3928b7c896e5a9fb6b1373924adafe8e01a0c6	2025-02-17
https://git.kernel.org/stable/c/974f85f1f7eb7dc7fce0988046e06eeccab576a7	2025-02-17

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				>= 6.14-rc1 < 6.14-rc2 Search vendor "Linux" for product "Linux Kernel" and version " >= 6.14-rc1 < 6.14-rc2"		en		Affected