x86/vmscape: Add conditional IBPB mitigation
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 ]
CVE-2025-40300
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2025-40300
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "ac60717f9a8d21c58617d0b34274babf24135835",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "c08192b5d6730a914dee6175bc71092ee6a65f14",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "d5490dfa35427a2967e00a4c7a1b95fdbc8ede34",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "15006289e5c38b2a830e1fba221977a27598176c",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "893387c18612bb452336a5881da0d015a7e8f4a2",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "f866eef8d1c65504d30923c3f14082ad294d0e6d",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "34e5667041050711a947e260fc9ebebe08bddee5",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "d7ddc93392e4a7ffcccc86edf6ef3e64c778db52",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "459274c77b37ac63b78c928b4b4e748d1f9d05c8",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "510603f504796c3535f67f55fb0b124a303b44c8",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "9c23a90648e831d611152ac08dbcd1283d405e7f",
"versionType": "git"
},
{
"status": "affected",
"version": "15d45071523d89b3fb7372e2135fbd72f6af9506",
"lessThan": "2f8f173413f1cbf52660d04df92d0069c4306d25",
"versionType": "git"
},
{
"status": "affected",
"version": "c51f1e5f57cca88d8d5894b6fad1638f643a99d0",
"versionType": "git"
},
{
"status": "affected",
"version": "4b3870c343a82cd2df7192cc5149c87205dcc611",
"versionType": "git"
},
{
"status": "affected",
"version": "3.16.57",
"lessThan": "3.17",
"versionType": "semver"
},
{
"status": "affected",
"version": "4.4.168",
"lessThan": "4.5",
"versionType": "semver"
}
],
"programFiles": [
"arch/x86/include/asm/cpufeatures.h",
"arch/x86/include/asm/entry-common.h",
"arch/x86/include/asm/nospec-branch.h",
"arch/x86/kernel/cpu/bugs.c",
"arch/x86/kvm/x86.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.16"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.16",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.244",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.193",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.152",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.106",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.47",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.16.7",
"versionType": "semver",
"lessThanOrEqual": "6.16.*"
},
{
"status": "unaffected",
"version": "6.17",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"arch/x86/include/asm/cpufeatures.h",
"arch/x86/include/asm/entry-common.h",
"arch/x86/include/asm/nospec-branch.h",
"arch/x86/kernel/cpu/bugs.c",
"arch/x86/kvm/x86.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2025-40300
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #27087 · Revision 1
- Added to Heist Feed
- Publisher date