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CVE-2025-68810— KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot

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，该漏洞源于允许在现有内存槽上清除KVM_MEM_GUEST_MEMFD标志，可能导致释放后重用。

CVSS 7.8 · High EPSS 0.15% · P4

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux a7800aa80ea4d5356b8474c2302812e9d4926fa6< 89dbbe6ff323fc34659621a577fe0af913f47386 affected
a7800aa80ea4d5356b8474c2302812e9d4926fa6< cb51bef465d8ec60a968507330e01020e35dc127 affected
a7800aa80ea4d5356b8474c2302812e9d4926fa6< 9935df5333aa503a18de5071f53762b65c783c4c affected
6.8 affected
< 6.8 unaffected
6.12.64≤ 6.12.* unaffected
6.18.3≤ 6.18.* unaffected
6.19≤ * unaffected
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I. Basic Information for CVE-2025-68810

Vulnerability Information
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Vulnerability Title
KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: KVM: Disallow toggling KVM_MEM_GUEST_MEMFD on an existing memslot Reject attempts to disable KVM_MEM_GUEST_MEMFD on a memslot that was initially created with a guest_memfd binding, as KVM doesn't support toggling KVM_MEM_GUEST_MEMFD on existing memslots. KVM prevents enabling KVM_MEM_GUEST_MEMFD, but doesn't prevent clearing the flag. Failure to reject the new memslot results in a use-after-free due to KVM not unbinding from the guest_memfd instance. Unbinding on a FLAGS_ONLY change is easy enough, and can/will be done as a hardening measure (in anticipation of KVM supporting dirty logging on guest_memfd at some point), but fixing the use-after-free would only address the immediate symptom. ================================================================== BUG: KASAN: slab-use-after-free in kvm_gmem_release+0x362/0x400 [kvm] Write of size 8 at addr ffff8881111ae908 by task repro/745 CPU: 7 UID: 1000 PID: 745 Comm: repro Not tainted 6.18.0-rc6-115d5de2eef3-next-kasan #3 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Call Trace: <TASK> dump_stack_lvl+0x51/0x60 print_report+0xcb/0x5c0 kasan_report+0xb4/0xe0 kvm_gmem_release+0x362/0x400 [kvm] __fput+0x2fa/0x9d0 task_work_run+0x12c/0x200 do_exit+0x6ae/0x2100 do_group_exit+0xa8/0x230 __x64_sys_exit_group+0x3a/0x50 x64_sys_call+0x737/0x740 do_syscall_64+0x5b/0x900 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f581f2eac31 </TASK> Allocated by task 745 on cpu 6 at 9.746971s: kasan_save_stack+0x20/0x40 kasan_save_track+0x13/0x50 __kasan_kmalloc+0x77/0x90 kvm_set_memory_region.part.0+0x652/0x1110 [kvm] kvm_vm_ioctl+0x14b0/0x3290 [kvm] __x64_sys_ioctl+0x129/0x1a0 do_syscall_64+0x5b/0x900 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Freed by task 745 on cpu 6 at 9.747467s: kasan_save_stack+0x20/0x40 kasan_save_track+0x13/0x50 __kasan_save_free_info+0x37/0x50 __kasan_slab_free+0x3b/0x60 kfree+0xf5/0x440 kvm_set_memslot+0x3c2/0x1160 [kvm] kvm_set_memory_region.part.0+0x86a/0x1110 [kvm] kvm_vm_ioctl+0x14b0/0x3290 [kvm] __x64_sys_ioctl+0x129/0x1a0 do_syscall_64+0x5b/0x900 entry_SYSCALL_64_after_hwframe+0x4b/0x53
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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，该漏洞源于允许在现有内存槽上清除KVM_MEM_GUEST_MEMFD标志，可能导致释放后重用。
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 a7800aa80ea4d5356b8474c2302812e9d4926fa6 ~ 89dbbe6ff323fc34659621a577fe0af913f47386 -
Linux Linux 6.8 -

II. Public POCs for CVE-2025-68810

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III. Intelligence Information for CVE-2025-68810

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Same Patch Batch · Linux · 2026-01-13 · 93 CVEs total

CVE-2025-71068 9.8 CRITICAL svcrdma: bound check rq_pages index in inline path
CVE-2025-68794 9.8 CRITICAL iomap: adjust read range correctly for non-block-aligned positions
CVE-2025-68811 9.8 CRITICAL svcrdma: use rc_pageoff for memcpy byte offset
CVE-2025-68817 9.8 CRITICAL ksmbd: fix use-after-free in ksmbd_tree_connect_put under concurrency
CVE-2025-68775 9.8 CRITICAL net/handshake: duplicate handshake cancellations leak socket
CVE-2025-68809 9.1 CRITICAL ksmbd: vfs: fix race on m_flags in vfs_cache
CVE-2025-71093 9.1 CRITICAL e1000: fix OOB in e1000_tbi_should_accept()
CVE-2025-71095 9.1 CRITICAL net: stmmac: fix the crash issue for zero copy XDP_TX action
CVE-2025-68818 8.8 HIGH scsi: Revert "scsi: qla2xxx: Perform lockless command completion in abort path"
CVE-2025-71072 8.2 HIGH shmem: fix recovery on rename failures
CVE-2025-68799 8.1 HIGH caif: fix integer underflow in cffrml_receive()
CVE-2025-68803 8.0 HIGH NFSD: NFSv4 file creation neglects setting ACL
CVE-2025-71078 7.8 HIGH powerpc/64s/slb: Fix SLB multihit issue during SLB preload
CVE-2025-68801 7.8 HIGH mlxsw: spectrum_router: Fix neighbour use-after-free
CVE-2025-71082 7.8 HIGH Bluetooth: btusb: revert use of devm_kzalloc in btusb
CVE-2025-68795 7.8 HIGH ethtool: Avoid overflowing userspace buffer on stats query
CVE-2025-68793 7.8 HIGH drm/amdgpu: fix a job->pasid access race in gpu recovery
CVE-2025-68822 7.8 HIGH Input: alps - fix use-after-free bugs caused by dev3_register_work
CVE-2025-68792 7.8 HIGH tpm2-sessions: Fix out of range indexing in name_size
CVE-2025-71066 7.8 HIGH net/sched: ets: Always remove class from active list before deleting in ets_qdisc_change

Showing top 20 of 93 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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