{
"schemaVersion": 1,
"attribution": [
{
"source": "CISA Known Exploited Vulnerabilities",
"url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
"licence": "US government work"
},
{
"source": "GitHub Advisory Database",
"url": "https://github.com/advisories",
"licence": "CC BY 4.0"
},
{
"source": "Have I Been Pwned",
"url": "https://haveibeenpwned.com/",
"licence": "CC BY 4.0"
},
{
"source": "CVE Program (CVE records)",
"url": "https://www.cve.org/Legal/TermsOfUse",
"licence": "CVE Terms of Use",
"notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
"terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
},
{
"source": "FIRST EPSS",
"url": "https://www.first.org/epss/",
"licence": "free to use; FIRST requests attribution"
}
],
"record": {
"id": "CVE-2026-23005",
"sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-23005",
"idYear": 2026,
"status": "PUBLISHED",
"publishedAt": "2026-01-25T14:36:19.021Z",
"updatedAt": "2026-10-19T18:25:27.665Z",
"importedAt": "2026-10-24T01:58:02.025Z",
"snapshot": {
"id": "cve_2026-10-24_midnight_baseline",
"at": "2026-10-24T00:00:00.000Z",
"source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
},
"facts": {
"title": "x86/fpu: Clear XSTATE_BV[i] in guest XSAVE state whenever XFD[i]=1",
"summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fpu: Clear XSTATE_BV[i] in guest XSAVE state whenever XFD[i]=1\n\nWhen loading guest XSAVE state via KVM_SET_XSAVE, and when updating XFD in\nresponse to a guest WRMSR, clear XFD-disabled features in the saved (or to\nbe restored) XSTATE_BV to ensure KVM doesn't attempt to load state for\nfeatures that are disabled via the guest's XFD. Because the kernel\nexecutes XRSTOR with the guest's XFD, saving XSTATE_BV[i]=1 with XFD[i]=1\nwill cause XRSTOR to #NM and panic the kernel.\n\nE.g. if fpu_update_guest_xfd() sets XFD without clearing XSTATE_BV:\n\n ------------[ cut here ]------------\n WARNING: arch/x86/kernel/traps.c:1524 at exc_device_not_available+0x101/0x110, CPU#29: amx_test/848\n Modules linked in: kvm_intel kvm irqbypass\n CPU: 29 UID: 1000 PID: 848 Comm: amx_test Not tainted 6.19.0-rc2-ffa07f7fd437-x86_amx_nm_xfd_non_init-vm #171 NONE\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:exc_device_not_available+0x101/0x110\n Call Trace:\n \n asm_exc_device_not_available+0x1a/0x20\n RIP: 0010:restore_fpregs_from_fpstate+0x36/0x90\n switch_fpu_return+0x4a/0xb0\n kvm_arch_vcpu_ioctl_run+0x1245/0x1e40 [kvm]\n kvm_vcpu_ioctl+0x2c3/0x8f0 [kvm]\n __x64_sys_ioctl+0x8f/0xd0\n do_syscall_64+0x62/0x940\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n \n ---[ end trace 0000000000000000 ]---\n\nThis can happen if the guest executes WRMSR(MSR_IA32_XFD) to set XFD[18] = 1,\nand a host IRQ triggers kernel_fpu_begin() prior to the vmexit handler's\ncall to fpu_update_guest_xfd().\n\nand if userspace stuffs XSTATE_BV[i]=1 via KVM_SET_XSAVE:\n\n ------------[ cut here ]------------\n WARNING: arch/x86/kernel/traps.c:1524 at exc_device_not_available+0x101/0x110, CPU#14: amx_test/867\n Modules linked in: kvm_intel kvm irqbypass\n CPU: 14 UID: 1000 PID: 867 Comm: amx_test Not tainted 6.19.0-rc2-2dace9faccd6-x86_amx_nm_xfd_non_init-vm #168 NONE\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n RIP: 0010:exc_device_not_available+0x101/0x110\n Call Trace:\n \n asm_exc_device_not_available+0x1a/0x20\n RIP: 0010:restore_fpregs_from_fpstate+0x36/0x90\n fpu_swap_kvm_fpstate+0x6b/0x120\n kvm_load_guest_fpu+0x30/0x80 [kvm]\n kvm_arch_vcpu_ioctl_run+0x85/0x1e40 [kvm]\n kvm_vcpu_ioctl+0x2c3/0x8f0 [kvm]\n __x64_sys_ioctl+0x8f/0xd0\n do_syscall_64+0x62/0x940\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\n \n ---[ end trace 0000000000000000 ]---\n\nThe new behavior is consistent with the AMX architecture. Per Intel's SDM,\nXSAVE saves XSTATE_BV as '0' for components that are disabled via XFD\n(and non-compacted XSAVE saves the initial configuration of the state\ncomponent):\n\n If XSAVE, XSAVEC, XSAVEOPT, or XSAVES is saving the state component i,\n the instruction does not generate #NM when XCR0[i] = IA32_XFD[i] = 1;\n instead, it operates as if XINUSE[i] = 0 (and the state component was\n in its initial state): it saves bit i of XSTATE_BV field of the XSAVE\n header as 0; in addition, XSAVE saves the initial configuration of the\n state component (the other instructions do not save state component i).\n\nAlternatively, KVM could always do XRSTOR with XFD=0, e.g. by using\na constant XFD based on the set of enabled features when XSAVEing for\na struct fpu_guest. However, having XSTATE_BV[i]=1 for XFD-disabled\nfeatures can only happen in the above interrupt case, or in similar\nscenarios involving preemption on preemptible kernels, because\nfpu_swap_kvm_fpstate()'s call to save_fpregs_to_fpstate() saves the\noutgoing FPU state with the current XFD; and that is (on all but the\nfirst WRMSR to XFD) the guest XFD.\n\nTherefore, XFD can only go out of sync with XSTATE_BV in the above\ninterrupt case, or in similar scenarios involving preemption on\npreemptible kernels, and it we can consider it (de facto) part of KVM\nABI that KVM_GET_XSAVE returns XSTATE_BV[i]=0 for XFD-disabled features.\n\n[Move clea\n---truncated---",
"affected": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"versions": [
{
"version": "820a6ee944e74e57255ac2e90916ecdaade57b95",
"status": "affected",
"versionType": "git",
"lessThan": "b5995c01ba53d84182ecb9492fc4d91cfe8a362d"
},
{
"version": "820a6ee944e74e57255ac2e90916ecdaade57b95",
"status": "affected",
"versionType": "git",
"lessThan": "1e2848bda819af569dfe7ab186223855e092a2cb"
},
{
"version": "820a6ee944e74e57255ac2e90916ecdaade57b95",
"status": "affected",
"versionType": "git",
"lessThan": "f577508cc8a0adb8b4ebe9480bba7683b6149930"
},
{
"version": "820a6ee944e74e57255ac2e90916ecdaade57b95",
"status": "affected",
"versionType": "git",
"lessThan": "eea6f395ca502c4528314c8112da9b5d65f685eb"
},
{
"version": "820a6ee944e74e57255ac2e90916ecdaade57b95",
"status": "affected",
"versionType": "git",
"lessThan": "b45f721775947a84996deb5c661602254ce25ce6"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"versions": [
{
"version": "5.17",
"status": "affected"
},
{
"version": "0",
"status": "unaffected",
"versionType": "semver",
"lessThan": "5.17"
},
{
"version": "6.1.162",
"status": "unaffected",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"version": "6.6.122",
"status": "unaffected",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"version": "6.12.67",
"status": "unaffected",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"version": "6.18.7",
"status": "unaffected",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"version": "6.19",
"status": "unaffected",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
]
}
]
}
}
}