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CVE-2026-64284— KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 6.12版本存在安全漏洞，该漏洞源于KVM在快速路径用户空间退出处理中未能在用户空间获得控制前运行供应商特定操作（如刷新PML缓冲区），可能导致内存写入不被标记为脏或使用过期状态。

CVSS 7.1 · High EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1059.012 · Hypervisor CLI

Affected Version Matrix 10

VendorProduct Version RangeStatus
Linux Linux f7f39c50edb9d336274371953275e0d3503b9b75< b3436d9b9b1affe1c3191ac9831308923f5f03c3 affected
f7f39c50edb9d336274371953275e0d3503b9b75< 4ad73ef0e7966ecfe67de0060537b4cb14d9acd4 affected
f7f39c50edb9d336274371953275e0d3503b9b75< f2ca2b5326211bd38490f0497eb583721ce0bbc0 affected
f7f39c50edb9d336274371953275e0d3503b9b75< 0ffedf43910e44b76c2c1db4e9fbf12b268190c1 affected
6.12 affected
< 6.12 unaffected
6.12.96≤ 6.12.* unaffected
6.18.39≤ 6.18.* unaffected
… +2 more rows
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I. Basic Information for CVE-2026-64284

Vulnerability Information
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Vulnerability Title
KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Ensure vendor's exit handler runs before fastpath userspace exits Move the handling of fastpath userspace exits into vendor code to ensure KVM runs vendor specific operations that need to run before userspace gains control of the vCPU. E.g. for VMX (and soon to be for SVM as well), KVM needs to flush the PML buffer prior to exiting to userspace, otherwise any memory written by the final KVM_RUN might never be flagged as dirty. Note, waiting to snapshot CR0 and CR3 until svm_handle_exit() is flawed in general, as that risks consuming stale state in a fastpath handler. That will be addressed in a future change.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 6.12版本存在安全漏洞，该漏洞源于KVM在快速路径用户空间退出处理中未能在用户空间获得控制前运行供应商特定操作（如刷新PML缓冲区），可能导致内存写入不被标记为脏或使用过期状态。
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

Vendor Product Affected Versions CPE Subscribe
Linux Linux f7f39c50edb9d336274371953275e0d3503b9b75 ~ b3436d9b9b1affe1c3191ac9831308923f5f03c3 -
Linux Linux 6.12 -

II. Public POCs for CVE-2026-64284

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III. Intelligence Information for CVE-2026-64284

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Patches & Fixes for CVE-2026-64284 (4)

Same Patch Batch · Linux · 2026-07-25 · 274 CVEs total

CVE-2026-64355 9.8 CRITICAL bpf: Reject fragmented frames in devmap
CVE-2026-64459 9.8 CRITICAL tcp: restore RCU grace period in tcp_ao_destroy_sock
CVE-2026-64303 9.8 CRITICAL spi: fsl-lpspi: terminate the RX channel on TX prepare failure path
CVE-2026-64439 9.8 CRITICAL crypto: krb5 - filter out async aead implementations at alloc
CVE-2026-64410 9.8 CRITICAL netfilter: flowtable: IPIP tunnel hardware offload is not yet support
CVE-2026-64399 9.8 CRITICAL ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE
CVE-2026-64397 9.8 CRITICAL ksmbd: serialize QUERY_DIRECTORY requests per file
CVE-2026-64391 9.8 CRITICAL ksmbd: use opener credentials for ADS I/O
CVE-2026-64387 9.8 CRITICAL smb: client: fix query directory replay double-free
CVE-2026-64386 9.8 CRITICAL smb: client: fix query_info() replay double-free
CVE-2026-64385 9.8 CRITICAL smb: client: fix double-free in SMB2_ioctl() replay
CVE-2026-64383 9.8 CRITICAL smb: client: fix double-free in SMB2_flush() replay
CVE-2026-64384 9.8 CRITICAL smb: client: fix change notify replay double-free
CVE-2026-64268 9.8 CRITICAL RDMA/siw: bound Read Response placement to the RREAD length
CVE-2026-64523 9.8 CRITICAL net/handshake: Take a long-lived file reference at submit
CVE-2026-64257 9.1 CRITICAL smb: client: reject overlapping data areas in SMB2 responses
CVE-2026-64392 9.1 CRITICAL ksmbd: use opener credentials for delete-on-close
CVE-2026-64393 9.1 CRITICAL ksmbd: run set info with opener credentials
CVE-2026-64269 9.1 CRITICAL RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg
CVE-2026-64319 9.1 CRITICAL nvmet-auth: validate reply message payload bounds against transfer length

Showing top 20 of 274 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64284

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