CVE Intelligence
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CVE-2023-53756 — KVM: VMX: Fix crash due to uninitialized current_vmcs

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

Published Dec 7, 2025 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+1

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.19%
ahead of 8% of scored CVEs · Oct 15, 2026
Affects
Linux
Linux
CVSS base
—
Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ ceef7d10dfb6284d512c499292e6daa35ea83f90 and < 6baebcecf09acd19e2bab1c2911dcdba5d48a1dc≥ ceef7d10dfb6284d512c499292e6daa35ea83f90 and < 6e7bc50f97c9855da83f1478f722590defd45ff2≥ ceef7d10dfb6284d512c499292e6daa35ea83f90 and < b2de2b4d4e007f9add46ea8dc06f781835e3ea9f≥ ceef7d10dfb6284d512c499292e6daa35ea83f90 and < 3ba95cc671c025d0d2a1c7d5e2930f0ff0980cf4≥ ceef7d10dfb6284d512c499292e6daa35ea83f90 and < 93827a0a36396f2fd6368a54a020f420c8916e9bversion 4.18 Vulnerable CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.19%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Not enough vector or weakness data: use the affected application’s logs as a starting point.
application logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Record published
    Oct 13, 2026
  • Affected products added · linux/linux
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · → Deferred
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • 2025
  • CVE published
    Dec 7, 2025 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

5 on the record

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

  • CVE-2026-99999 ipv4: validate checksum_start before completing checksum 17h
  • CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 17h
  • CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 1d
  • CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
  • CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
  • CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CVSS score published by NVD, the CNA, CISA or GitHub so far.
  • No fixed version, patch or mitigation documented.
  • No CISA SSVC assessment.
  • No CWE classification.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2023-53756 is "KVM: VMX: Fix crash due to uninitialized current_vmcs", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.19% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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