{"id":"CVE-2022-49559","state":"PUBLISHED","title":"KVM: x86: Drop WARNs that assert a triple fault never \"escapes\" from L2","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 ]---","publishedAt":"2025-02-26T02:14:05.059Z","updatedAt":"2026-05-11T19:02:17.480Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"8d3a2aa0976f57320ba89baf9d57fb158dd0cd0d","versionType":"git"},{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"f476a59d5c86c02a79eef893c6da86735f2977ac","versionType":"git"},{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"7de373c9b48229e428ecdb8fbde269c5a8617fd2","versionType":"git"},{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"45846661d10422ce9e22da21f8277540b29eca22","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/vmx/nested.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.13","versionType":"semver"},{"version":"5.15.45","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.17.13","status":"unaffected","lessThanOrEqual":"5.17.*","versionType":"semver"},{"version":"5.18.2","status":"unaffected","lessThanOrEqual":"5.18.*","versionType":"semver"},{"version":"5.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/vmx/nested.c"]}],"references":["https://git.kernel.org/stable/c/8d3a2aa0976f57320ba89baf9d57fb158dd0cd0d","https://git.kernel.org/stable/c/f476a59d5c86c02a79eef893c6da86735f2977ac","https://git.kernel.org/stable/c/7de373c9b48229e428ecdb8fbde269c5a8617fd2","https://git.kernel.org/stable/c/45846661d10422ce9e22da21f8277540b29eca22"],"weaknesses":[],"ingestedAt":"2026-10-29T20:05:26.763Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2022/49xxx/CVE-2022-49559.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2022-49559","state":"PUBLISHED","datePublished":"2025-02-26T02:14:05.059Z","dateUpdated":"2026-05-11T19:02:17.480Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-02-26T02:08:31.591Z"},"containers":{"cna":{"title":"KVM: x86: Drop WARNs that assert a triple fault never \"escapes\" from L2","descriptions":[{"lang":"en","value":"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 ]---"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"8d3a2aa0976f57320ba89baf9d57fb158dd0cd0d","versionType":"git"},{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"f476a59d5c86c02a79eef893c6da86735f2977ac","versionType":"git"},{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"7de373c9b48229e428ecdb8fbde269c5a8617fd2","versionType":"git"},{"version":"cb6a32c2b8777ad31a02e585584d869251a790e3","status":"affected","lessThan":"45846661d10422ce9e22da21f8277540b29eca22","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/vmx/nested.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.13","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.13","versionType":"semver"},{"version":"5.15.45","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.17.13","status":"unaffected","lessThanOrEqual":"5.17.*","versionType":"semver"},{"version":"5.18.2","status":"unaffected","lessThanOrEqual":"5.18.*","versionType":"semver"},{"version":"5.19","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/kvm/svm/nested.c","arch/x86/kvm/vmx/nested.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/8d3a2aa0976f57320ba89baf9d57fb158dd0cd0d"},{"url":"https://git.kernel.org/stable/c/f476a59d5c86c02a79eef893c6da86735f2977ac"},{"url":"https://git.kernel.org/stable/c/7de373c9b48229e428ecdb8fbde269c5a8617fd2"},{"url":"https://git.kernel.org/stable/c/45846661d10422ce9e22da21f8277540b29eca22"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T19:02:17.480Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"5.15.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"5.17.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"5.18.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13","versionEndExcluding":"5.19"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}