🛡️ CVE-2023-53663 on Debian — linux

⚪ Unknown ✅ No Known Exploit OSV
N/A
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: nSVM: Check instead of asserting on nested TSC scaling support Check for nested TSC scaling support on nested SVM VMRUN instead of asserting that TSC scaling is exposed to L1 if L1's MSR_AMD64_TSC_RATIO has diverged from KVM's default. Userspace can trigger the WARN at will by writing the MSR and then updating guest CPUID to hide the feature (modifying guest CPUID is allowed anytime before KVM_RUN). E.g. hacking KVM's state_test selftest to do vcpu_set_msr(vcpu, MSR_AMD64_TSC_RATIO, 0); vcpu_clear_cpuid_feature(vcpu, X86_FEATURE_TSCRATEMSR); after restoring state in a new VM+vCPU yields an endless supply of: ------------[ cut here ]------------ WARNING: CPU: 164 PID: 62565 at arch/x86/kvm/svm/nested.c:699 nested_vmcb02_prepare_control+0x3d6/0x3f0 [kvm_amd] Call Trace: <TASK> enter_svm_guest_mode+0x114/0x560 [kvm_amd] nested_svm_vmrun+0x260/0x330 [kvm_amd] vmrun_interception+0x29/0x30 [kvm_amd] svm_invoke_exit_handler+0x35/0x100 [kvm_amd] svm_handle_exit+0xe7/0x180 [kvm_amd] kvm_arch_vcpu_ioctl_run+0x1eab/0x2570 [kvm] kvm_vcpu_ioctl+0x4c9/0x5b0 [kvm] __se_sys_ioctl+0x7a/0xc0 __x64_sys_ioctl+0x21/0x30 do_syscall_64+0x41/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x45ca1b Note, the nested #VMEXIT path has the same flaw, but needs a different fix and will be handled separately.

Distribution advisory

This page covers CVE-2023-53663 as tracked by Debian, for the package linux. The fix is available in version 6.5.6-1; earlier versions remain affected.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.

Affected software

DEBIAN-CVE-2023-53663 is recorded against 1 package.

  • linux (fixed in 6.5.6-1)

Timeline and source

Published on 7 October 2025 and last revised on 7 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

security-tracker.debian.org (Advisory)

CVE-2023-53663 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity Unknown
CVSS Score N/A
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2025-10-07
Updated 2026-08-12
Modified 2026-08-07
Fix URL N/A

Affected Packages

Software From version Fixed in
linux — 6.5.6-1

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