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Fencer Vulns
no cvss —

CVE-2023-53756 json

KVM: VMX: Fix crash due to uninitialized current_vmcs

published 2025-12-08 11 mo ago modified 2026-06-17 4 mo ago also EUVD-2023-60072

cvss
—
not scored
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

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

KVM: VMX: Fix crash due to uninitialized current_vmcs

KVM enables 'Enlightened VMCS' and 'Enlightened MSR Bitmap' when running as a nested hypervisor on top of Hyper-V. When MSR bitmap is updated, evmcs_touch_msr_bitmap function uses current_vmcs per-cpu variable to mark that the msr bitmap was changed.

vmx_vcpu_create() modifies the msr bitmap via vmx_disable_intercept_for_msr -> vmx_msr_bitmap_l01_changed which in the end calls this function. The function checks for current_vmcs if it is null but the check is insufficient because current_vmcs is not initialized. Because of this, the code might incorrectly write to the structure pointed by current_vmcs value left by another task. Preemption is not disabled, the current task can be preempted and moved to another CPU while current_vmcs is accessed multiple times from evmcs_touch_msr_bitmap() which leads to crash.

The manipulation of MSR bitmaps by callers happens only for vmcs01 so the solution is to use vmx->vmcs01.vmcs instead of current_vmcs.

BUG: kernel NULL pointer dereference, address: 0000000000000338 PGD 4e1775067 P4D 0 Oops: 0002 [#1] PREEMPT SMP NOPTI ... RIP: 0010:vmx_msr_bitmap_l01_changed+0x39/0x50 [kvm_intel] ... Call Trace: vmx_disable_intercept_for_msr+0x36/0x260 [kvm_intel] vmx_vcpu_create+0xe6/0x540 [kvm_intel] kvm_arch_vcpu_create+0x1d1/0x2e0 [kvm] kvm_vm_ioctl_create_vcpu+0x178/0x430 [kvm] kvm_vm_ioctl+0x53f/0x790 [kvm] __x64_sys_ioctl+0x8a/0xc0 do_syscall_64+0x5c/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Patch / fix

  • Linux Linux 5.10.175, 5.15.103, 6.1.16, 6.2.3, 6.3
  • linux Debian 14, Debian 13, Debian 12 6.1.20-1

debian advisories DEBIAN-CVE-2023-53756

  • linux Ubuntu 22.04 LTS 5.15.0-79.86
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1042.47
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1039.47
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1039.44
  • linux-ibm Ubuntu 22.04 LTS 5.15.0-1035.38
  • linux-kvm Ubuntu 22.04 LTS 5.15.0-1039.44
  • linux-azure Ubuntu 22.04 LTS 5.15.0-1045.52
  • linux-gkeop Ubuntu 22.04 LTS 5.15.0-1025.30

ubuntu advisories UBUNTU-CVE-2023-53756

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-362.8.1.el9_3
  • rv RHEL 9 5.14.0-362.8.1.el9_3
  • perf RHEL 9 5.14.0-362.8.1.el9_3
  • rtla RHEL 9 5.14.0-362.8.1.el9_3
  • bpftool RHEL 9 7.2.0-362.8.1.el9_3
  • libperf RHEL 9 5.14.0-362.8.1.el9_3
  • kernel-rt RHEL 9 5.14.0-362.8.1.el9_3
  • kernel-64k RHEL 9 5.14.0-362.8.1.el9_3

red hat advisories RHSA-2023:6583RHSA-2023:3465

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-53756 updated cvss 5.5

kernel: KVM: VMX: Fix crash due to uninitialized current_vmcs

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
    affected: no fix available “Fix deferred”
  • Red Hat CodeReady Linux Builder EUS (v.9.0) kernel-debuginfo-common-s390x 5.14.0-70.58.1.el9_0, kernel-debuginfo-common-x86_64 5.14.0-70.58.1.el9_0, kernel-debuginfo-common-aarch64 5.14.0-70.58.1.el9_0, kernel-debuginfo-common-ppc64le 5.14.0-70.58.1.el9_0 Red Hat Enterprise Linux AppStream EUS (v.9.0) perf 5.14.0-70.58.1.el9_0, kernel-devel-matched 5.14.0-70.58.1.el9_0, kernel-debug-devel-matched 5.14.0-70.58.1.el9_0, kernel-debuginfo-common-s390x 5.14.0-70.58.1.el9_0, kernel-zfcpdump-devel-matched 5.14.0-70.58.1.el9_0, kernel-debuginfo-common-x86_64 5.14.0-70.58.1.el9_0, +2 more Red Hat Enterprise Linux BaseOS EUS (v.9.0) kernel 5.14.0-70.58.1.el9_0, bpftool 5.14.0-70.58.1.el9_0, kernel-core 5.14.0-70.58.1.el9_0, kernel-tools 5.14.0-70.58.1.el9_0, python3-perf 5.14.0-70.58.1.el9_0, kernel-modules 5.14.0-70.58.1.el9_0, +14 more
    fixed: vendor fix RHSA-2023:3465
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.20% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-08).

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

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