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National Vulnerability Database

National Vulnerability Database

NVD

National Vulnerability Database
  1. Vulnerabilities

CVE-2025-40300 Detail

Description

In the Linux kernel, the following vulnerability has been resolved: x86/vmscape: Add conditional IBPB mitigation VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit. Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB. This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace. The intent is to integrate and optimize these cases post-embargo. [ dhansen: elaborate on suboptimal IBPB solution ]


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NIST CVSS score
NIST: NVD
N/A
NVD assessment not yet provided.

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URL Source(s) Tag(s)
https://git.kernel.org/stable/c/15006289e5c38b2a830e1fba221977a27598176c kernel.org
https://git.kernel.org/stable/c/2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e kernel.org
https://git.kernel.org/stable/c/34e5667041050711a947e260fc9ebebe08bddee5 kernel.org
https://git.kernel.org/stable/c/459274c77b37ac63b78c928b4b4e748d1f9d05c8 kernel.org
https://git.kernel.org/stable/c/510603f504796c3535f67f55fb0b124a303b44c8 kernel.org
https://git.kernel.org/stable/c/893387c18612bb452336a5881da0d015a7e8f4a2 kernel.org
https://git.kernel.org/stable/c/9c23a90648e831d611152ac08dbcd1283d405e7f kernel.org
https://git.kernel.org/stable/c/ac60717f9a8d21c58617d0b34274babf24135835 kernel.org
https://git.kernel.org/stable/c/c08192b5d6730a914dee6175bc71092ee6a65f14 kernel.org
https://git.kernel.org/stable/c/d5490dfa35427a2967e00a4c7a1b95fdbc8ede34 kernel.org
https://git.kernel.org/stable/c/d7ddc93392e4a7ffcccc86edf6ef3e64c778db52 kernel.org
https://git.kernel.org/stable/c/f866eef8d1c65504d30923c3f14082ad294d0e6d kernel.org

Weakness Enumeration

CWE-ID CWE Name Source

Change History

1 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2025-40300
NVD Published Date:
09/11/2025
NVD Last Modified:
09/11/2025
Source:
kernel.org