CVE-2023-53663

Host denial of service via nested TSC assertion

Published Oct 7, 2025 · Updated Oct 7, 2025

Reachable assertion in Linux KVM nSVM allows local users to interrupt host service by entering a nested guest with inconsistent TSC state. nested_vmcb02_prepare_control asserts that TSC scaling is exposed after the guest TSC ratio diverges, rather than checking the guest CPUID feature first. Exploitation requires local access to a KVM virtual CPU on an AMD host and causes repeated kernel warnings without reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in Linux KVM nSVM allows local users to interrupt host service by entering a nested guest with inconsistent TSC state. nested_vmcb02_prepare_control asserts that TSC scaling is exposed after the guest TSC ratio diverges, rather than checking the guest CPUID feature first. Exploitation requires local access to a KVM virtual CPU on an AMD host and causes repeated kernel warnings without reported data disclosure or modification.

The record

CVE
CVE-2023-53663
Published
Oct 7, 2025
Updated
Oct 7, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 7, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 7, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.16
  2. Affected versionversion=5228eb96a4875f8cf5d61d486e3795ac14df8904 <02b24270568f65dd607c4a848512dc8055b4491b
  3. Affected versionversion=5228eb96a4875f8cf5d61d486e3795ac14df8904 <6c1ecfea1daf6e75c46e295aad99dfbafd878897
  4. Affected versionversion=5228eb96a4875f8cf5d61d486e3795ac14df8904 <7cafe9b8e22bb3d77f130c461aedf6868c4aaf58

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.16; version=5228eb96a4875f8cf5d61d486e3795ac14df8904 <02b24270568f65dd607c4a848512dc8055b4491b; version=5228eb96a4875f8cf5d61d486e3795ac14df8904 <6c1ecfea1daf6e75c46e295aad99dfbafd878897; version=5228eb96a4875f8cf5d61d486e3795ac14df8904 <7cafe9b8e22bb3d77f130c461aedf6868c4aaf58

Published CVSS scores

5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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