CVE-2026-80853
Received Received - Intake

Memory Corruption in Linux Kernel KVM SEV-SNP

Publication date: 2026-09-04

Last updated on: 2026-09-04

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Allocate full pages for {DE,EN}CRYPT ops on SNP-enabled hosts When {de,en}crypting memory of an SEV or SEV-ES guest on an SNP-enabled host via a temporary buffer, allocate a full 4KiB page for the buffer to ensure the page containing the buffer is wholly owned by KVM, i.e. won't be concurrently allocated and accessed by other kernel code while KVM is using the buffer to {de,en}crypt memory. On SNP-enabled platforms, when sending SEV/SEV-ES commands that trigger firmware writes to memory, the to-be-written page(s) must be (temporarily) assigned to Firmware (as required by the SNP architecture, to guard against using such commands as gadgets to attack SNP guests). See snp_map_cmd_buf_desc() and friends. Unfortunately, transferring ownership of a page to Firmware makes the page inaccessible to software, and thus writes generate RMP #PF violations. If KVM uses a sub-page allocation for its temporary buffer, some other actor in the kernel can allocate and use the other portions of the page, and thus trigger unexpected (and seemingly spurious) RMP #PF violations due to software attempting to access a Firmware-owned page. BUG: unable to handle page fault for address: ffff906ae30f0300 #PF: supervisor write access in kernel mode #PF: error_code(0x80000003) - RMP violation PGD 6b1b80d067 P4D 6b1b80d067 PUD 100231e2063 PMD 10055a88063 PTE 80000100630f0163 SEV-SNP: PFN 0x100630f0 unassigned, dumping non-zero entries in 2M PFN region: [0x10063000 - 0x10063200] Oops: Oops: 0003 [#1] SMP CPU: 70 UID: 0 PID: 10658 Comm: svw_WaiterThrea Tainted: G U W O 7.1.0-smp--c22293789940-seanjc-next #1 PREEMPTLAZY Tainted: [U]=USER, [W]=WARN, [O]=OOT_MODULE Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.86.0-102 01/25/2026 RIP: 0010:memset+0xf/0x20 Call Trace: <TASK> __kvmalloc_node_noprof+0x2a4/0x710 do_getxattr+0x4e/0x130 path_getxattrat+0x125/0x1b0 do_syscall_64+0x10a/0x480 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7f3a22cb6daa </TASK> Modules linked in: kvm_amd kvm irqbypass vfat fat ccp k10temp sha3 libsha3 i2c_piix4 gq(O) cdc_acm xhci_pci xhci_hcd gsmi: Log Shutdown Reason 0x03 CR2: ffff906ae30f0300 ---[ end trace 0000000000000000 ]--- RIP: 0010:memset+0xf/0x20 Kernel panic - not syncing: Fatal exception Kernel Offset: 0x39e00000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) gsmi: Log Shutdown Reason 0x02

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Meta Information

Published
2026-09-04
Last Modified
2026-09-04
Generated
2026-09-04
AI Q&A
2026-09-04
EPSS Evaluated
N/A
NVD
CVE-2026-80853
EUVD
EUVD-2026-71303

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux kernel to 7.1.0 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This vulnerability in the Linux kernel affects SEV and SEV-ES guests on SNP-enabled hosts. When decrypting or encrypting memory via a temporary buffer, KVM must allocate a full 4KiB page to ensure exclusive access. If a smaller buffer is used, other kernel processes might access the remaining parts of the page, causing RMP page fault violations when the page is temporarily assigned to firmware for SEV commands.

Detection Guidance

This vulnerability is specific to the Linux kernel's KVM module with SEV/SNP features. Detection requires checking kernel logs for RMP violation errors or kernel oops messages related to SEV-SNP. Look for errors like 'RMP violation' or 'SEV-SNP: PFN unassigned' in system logs. No direct network detection commands are applicable as this is a local kernel issue.

Impact Analysis

This vulnerability can cause kernel crashes, system instability, or denial of service due to page faults and potential kernel panics. Systems using AMD SEV or SEV-ES with SNP-enabled hosts are affected, leading to unexpected errors during memory encryption/decryption operations.

Mitigation Strategies

Apply the latest kernel patches that resolve this issue. If using SEV/SNP features, ensure your kernel version includes the fix for allocating full pages for {de,en}crypt operations. Monitor for kernel crashes or RMP violations in logs. Disable SEV/SNP features if not required until patched.

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