{"cve":"CVE-2022-49559","nvd":{"published":"2025-02-26T07:01:31.687","modified":"2026-06-17T05:18:26.850","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: x86: Drop WARNs that assert a triple fault never \"escapes\" from L2\n\nRemove WARNs that sanity check that KVM never lets a triple fault for L2\nescape and incorrectly end up in L1.  In normal operation, the sanity\ncheck is perfectly valid, but it incorrectly assumes that it's impossible\nfor userspace to induce KVM_REQ_TRIPLE_FAULT without bouncing through\nKVM_RUN (which guarantees kvm_check_nested_state() will see and handle\nthe triple fault).\n\nThe WARN can currently be triggered if userspace injects a machine check\nwhile L2 is active and CR4.MCE=0.  And a future fix to allow save/restore\nof KVM_REQ_TRIPLE_FAULT, e.g. so that a synthesized triple fault isn't\nlost on migration, will make it trivially easy for userspace to trigger\nthe WARN.\n\nClearing KVM_REQ_TRIPLE_FAULT when forcibly leaving guest mode is\ntempting, but wrong, especially if/when the request is saved/restored,\ne.g. if userspace restores events (including a triple fault) and then\nrestores nested state (which may forcibly leave guest mode).  Ignoring\nthe fact that KVM doesn't currently provide the necessary APIs, it's\nuserspace's responsibility to manage pending events during save/restore.\n\n  ------------[ cut here ]------------\n  WARNING: CPU: 7 PID: 1399 at arch/x86/kvm/vmx/nested.c:4522 nested_vmx_vmexit+0x7fe/0xd90 [kvm_intel]\n  Modules linked in: kvm_intel kvm irqbypass\n  CPU: 7 PID: 1399 Comm: state_test Not tainted 5.17.0-rc3+ #808\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  RIP: 0010:nested_vmx_vmexit+0x7fe/0xd90 [kvm_intel]\n  Call Trace:\n   <TASK>\n   vmx_leave_nested+0x30/0x40 [kvm_intel]\n   vmx_set_nested_state+0xca/0x3e0 [kvm_intel]\n   kvm_arch_vcpu_ioctl+0xf49/0x13e0 [kvm]\n   kvm_vcpu_ioctl+0x4b9/0x660 [kvm]\n   __x64_sys_ioctl+0x83/0xb0\n   do_syscall_64+0x3b/0xc0\n   entry_SYSCALL_64_after_hwframe+0x44/0xae\n   </TASK>\n  ---[ end trace 0000000000000000 ]---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/45846661d10422ce9e22da21f8277540b29eca22","https://git.kernel.org/stable/c/7de373c9b48229e428ecdb8fbde269c5a8617fd2","https://git.kernel.org/stable/c/8d3a2aa0976f57320ba89baf9d57fb158dd0cd0d","https://git.kernel.org/stable/c/f476a59d5c86c02a79eef893c6da86735f2977ac"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:59:48.811064707+00:00"},"epss":{"cve":"CVE-2022-49559","score":0.00299,"percentile":0.2259,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}