CVE-2026-31593— KVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU
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I. Basic Information for CVE-2026-31593
Vulnerability Information
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Vulnerability Title
KVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Reject attempts to sync VMSA of an already-launched/encrypted vCPU Reject synchronizing vCPU state to its associated VMSA if the vCPU has already been launched, i.e. if the VMSA has already been encrypted. On a host with SNP enabled, accessing guest-private memory generates an RMP #PF and panics the host. BUG: unable to handle page fault for address: ff1276cbfdf36000 #PF: supervisor write access in kernel mode #PF: error_code(0x80000003) - RMP violation PGD 5a31801067 P4D 5a31802067 PUD 40ccfb5063 PMD 40e5954063 PTE 80000040fdf36163 SEV-SNP: PFN 0x40fdf36, RMP entry: [0x6010fffffffff001 - 0x000000000000001f] Oops: Oops: 0003 [#1] SMP NOPTI CPU: 33 UID: 0 PID: 996180 Comm: qemu-system-x86 Tainted: G OE Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE Hardware name: Dell Inc. PowerEdge R7625/0H1TJT, BIOS 1.5.8 07/21/2023 RIP: 0010:sev_es_sync_vmsa+0x54/0x4c0 [kvm_amd] Call Trace: <TASK> snp_launch_update_vmsa+0x19d/0x290 [kvm_amd] snp_launch_finish+0xb6/0x380 [kvm_amd] sev_mem_enc_ioctl+0x14e/0x720 [kvm_amd] kvm_arch_vm_ioctl+0x837/0xcf0 [kvm] kvm_vm_ioctl+0x3fd/0xcc0 [kvm] __x64_sys_ioctl+0xa3/0x100 x64_sys_call+0xfe0/0x2350 do_syscall_64+0x81/0x10f0 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7ffff673287d </TASK> Note, the KVM flaw has been present since commit ad73109ae7ec ("KVM: SVM: Provide support to launch and run an SEV-ES guest"), but has only been actively dangerous for the host since SNP support was added. With SEV-ES, KVM would "just" clobber guest state, which is totally fine from a host kernel perspective since userspace can clobber guest state any time before sev_launch_update_vmsa().
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
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KVM SEV允许同步已启动加密vCPU的VMSA，访问客户私有内存时触发RMP异常导致主机崩溃。
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
II. Public POCs for CVE-2026-31593
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Same Patch Batch · Linux · 2026-04-24 · 138 CVEs total
| CVE-2026-31637 | 9.8 CRITICAL | rxrpc: reject undecryptable rxkad response tickets |
| CVE-2026-31609 | 9.8 CRITICAL | smb: client: avoid double-free in smbd_free_send_io() after smbd_send_batch_flush() |
| CVE-2026-31608 | 9.8 CRITICAL | smb: server: avoid double-free in smb_direct_free_sendmsg after smb_direct_flush_send_list |
| CVE-2026-31633 | 9.8 CRITICAL | rxrpc: Fix integer overflow in rxgk_verify_response() |
| CVE-2026-31657 | 9.8 CRITICAL | batman-adv: hold claim backbone gateways by reference |
| CVE-2026-31669 | 9.8 CRITICAL | mptcp: fix slab-use-after-free in __inet_lookup_established |
| CVE-2026-31668 | 9.8 CRITICAL | seg6: separate dst_cache for input and output paths in seg6 lwtunnel |
| CVE-2026-31607 | 9.8 CRITICAL | usbip: validate number_of_packets in usbip_pack_ret_submit() |
| CVE-2026-31536 | 9.8 CRITICAL | smb: server: let send_done handle a completion without IB_SEND_SIGNALED |
| CVE-2026-31659 | 9.8 CRITICAL | batman-adv: reject oversized global TT response buffers |
| CVE-2026-31649 | 9.8 CRITICAL | net: stmmac: fix integer underflow in chain mode |
| CVE-2026-31589 | 9.8 CRITICAL | mm: call ->free_folio() directly in folio_unmap_invalidate() |
| CVE-2026-31636 | 9.1 CRITICAL | rxrpc: fix RESPONSE authenticator parser OOB read |
| CVE-2026-31570 | 8.8 HIGH | can: gw: fix OOB heap access in cgw_csum_crc8_rel() |
| CVE-2026-31558 | 8.8 HIGH | LoongArch: KVM: Make kvm_get_vcpu_by_cpuid() more robust |
| CVE-2026-31553 | 8.8 HIGH | KVM: arm64: Fix the descriptor address in __kvm_at_swap_desc() |
| CVE-2026-31588 | 8.8 HIGH | KVM: x86: Use scratch field in MMIO fragment to hold small write values |
| CVE-2026-31629 | 8.8 HIGH | nfc: llcp: add missing return after LLCP_CLOSED checks |
| CVE-2026-31622 | 8.8 HIGH | NFC: digital: Bounds check NFC-A cascade depth in SDD response handler |
| CVE-2026-31611 | 8.6 HIGH | ksmbd: require 3 sub-authorities before reading sub_auth[2] |
Showing top 20 of 138 CVEs. View all on vendor page → →
IV. Related Vulnerabilities
Same product: Linux
- CVE-2026-43500
rxrpc: Also unshare DATA/RESPONSE packets when paged frags a - CVE-2026-43475
scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT - CVE-2026-43474
fs: init flags_valid before calling vfs_fileattr_get - CVE-2026-43473
scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
Same vendor: Linux
- CVE-2026-43500
rxrpc: Also unshare DATA/RESPONSE packets when paged frags a - CVE-2026-43475
scsi: storvsc: Fix scheduling while atomic on PREEMPT_RT - CVE-2026-43474
fs: init flags_valid before calling vfs_fileattr_get - CVE-2026-43473
scsi: mpi3mr: Add NULL checks when resetting request and rep - CVE-2026-43472
unshare: fix unshare_fs() handling
V. Comments for CVE-2026-31593
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