# CVE-2026-31592

> Vulnerability · severity: **MEDIUM** (CVSS 5.5).

## Description

In the Linux kernel, the following vulnerability has been resolved:

KVM: SEV: Protect *all* of sev_mem_enc_register_region() with kvm->lock

Take and hold kvm->lock for before checking sev_guest() in
sev_mem_enc_register_region(), as sev_guest() isn't stable unless kvm->lock
is held (or KVM can guarantee KVM_SEV_INIT{2} has completed and can't
rollack state).  If KVM_SEV_INIT{2} fails, KVM can end up trying to add to
a not-yet-initialized sev->regions_list, e.g. triggering a #GP

  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
  KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
  CPU: 110 UID: 0 PID: 72717 Comm: syz.15.11462 Tainted: G     U  W  O        6.16.0-smp-DEV #1 NONE
  Tainted: [U]=USER, [W]=WARN, [O]=OOT_MODULE
  Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.52.0-0 10/28/2024
  RIP: 0010:sev_mem_enc_register_region+0x3f0/0x4f0 ../include/linux/list.h:83
  Code: <41> 80 3c 04 00 74 08 4c 89 ff e8 f1 c7 a2 00 49 39 ed 0f 84 c6 00
  RSP: 0018:ffff88838647fbb8 EFLAGS: 00010256
  RAX: dffffc0000000000 RBX: 1ffff92015cf1e0b RCX: dffffc0000000000
  RDX: 0000000000000000 RSI: 0000000000001000 RDI: ffff888367870000
  RBP: ffffc900ae78f050 R08: ffffea000d9e0007 R09: 1ffffd4001b3c000
  R10: dffffc0000000000 R11: fffff94001b3c001 R12: 0000000000000000
  R13: ffff8982ab0bde00 R14: ffffc900ae78f058 R15: 0000000000000000
  FS:  00007f34e9dc66c0(0000) GS:ffff89ee64d33000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007fe180adef98 CR3: 000000047210e000 CR4: 0000000000350ef0
  Call Trace:
   <TASK>
   kvm_arch_vm_ioctl+0xa72/0x1240 ../arch/x86/kvm/x86.c:7371
   kvm_vm_ioctl+0x649/0x990 ../virt/kvm/kvm_main.c:5363
   __se_sys_ioctl+0x101/0x170 ../fs/ioctl.c:51
   do_syscall_x64 ../arch/x86/entry/syscall_64.c:63 [inline]
   do_syscall_64+0x6f/0x1f0 ../arch/x86/entry/syscall_64.c:94
   entry_SYSCALL_64_after_hwframe+0x76/0x7e

## Key facts

- **CVE ID:** CVE-2026-31592
- **Published:** 2026-04-24
- **CVSS severity:** MEDIUM
- **CVSS base score:** 5.5
- **CWE codes:** CWE-476

## Affected products

- `linux:linux_kernel`

## Primary sources

- NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31592

## Citation

> AI Analytics. CVE-2026-31592. Retrieved 2026-08-02 from https://api.ai-analytics.org/cve/CVE-2026-31592. Derived from NIST NVD. Licensed CC0.

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