{"api_version":"1","generated_at":"2026-08-13T21:33:06+00:00","cve":"CVE-2026-68093","urls":{"html":"https://cve.report/CVE-2026-68093","api":"https://cve.report/api/cve/CVE-2026-68093.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-68093","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-68093"},"summary":{"title":"KVM: SVM: Bump asid_generation on CPU online to avoid ASID collision after hotplug","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Bump asid_generation on CPU online to avoid ASID collision after hotplug\n\nIf a vCPU stays scheduled out (or blocked) while the last pCPU it ran\non goes through a hotplug cycle (online->offline->online), and the vCPU\nthen resumes execution on the same pCPU, then it is possible for it to\nrun with an ASID that has now been assigned to a different vCPU,\nresulting in stale TLB translations being used.\n\nsvm_enable_virtualization_cpu() resets asid_generation to 1 and sets\nnext_asid to max_asid + 1 on every CPU online event, including hotplug\ncycles.  Because next_asid starts beyond the pool boundary, the first\ncall to new_asid() after an online event always wraps the pool,\nincrementing asid_generation to 2 and assigning ASIDs starting from\nmin_asid.\n\nConsider two vCPUs from different VMs, vCPU-A pinned to CPU-X holding\nasid_generation=2 and ASID=N from before the hotplug event:\n\n  1. CPU-X goes offline and back online: asid_generation resets to 1,\n     next_asid = max_asid + 1.\n\n  2. One or more vCPUs migrate to CPU-X and call new_asid(), wrapping\n     the pool and consuming ASIDs starting from min_asid.  Eventually\n     vCPU-B from a different VM is assigned asid_generation=2, ASID=N\n     — the same ASID that vCPU-A held before the hotplug.\n\n  3. vCPU-A enters pre_svm_run() on CPU-X: current_vmcb->cpu is\n     unchanged so the migration branch is skipped.  Its saved\n     asid_generation=2 matches sd->asid_generation=2, so the generation\n     check silently passes and vCPU-A continues running with ASID=N —\n     the same ASID just freshly assigned to vCPU-B.\n\nBoth vCPUs from different VMs now run on CPU-X with the same ASID,\ncausing them to share NPT TLB entries and producing stale translations.\n\nThe collision manifests as a KVM internal error (Suberror: 1, emulation\nfailure).  The NPT page fault reports a faulting GPA far outside the\nVM's physical memory range — a sign of stale TLB translations being\nused.  KVM falls back to instruction emulation, which fails on\nFPU/XSave instructions (XRSTOR, STMXCSR) that the emulator does not\nimplement.\n\nFix this by incrementing asid_generation instead of resetting it to 1\nin svm_enable_virtualization_cpu().  On module load, asid_generation\nstarts at 0 (memset) and the increment produces 1, identical to the\nold behaviour.  On subsequent hotplug cycles the generation advances\nbeyond any value a vCPU previously observed on this CPU, so the\ngeneration check in pre_svm_run() reliably forces new_asid() on every\nvCPU after every hotplug cycle.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-08-10 13:19:53","updated_at":"2026-08-10 13:19:53"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/0f33b1c457c2199ed130b92cc2ff363a3f7b9415","name":"https://git.kernel.org/stable/c/0f33b1c457c2199ed130b92cc2ff363a3f7b9415","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/7508916b4b55d6f5ecc68cd09774dabd3a6b4440","name":"https://git.kernel.org/stable/c/7508916b4b55d6f5ecc68cd09774dabd3a6b4440","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/25f744ffa0c8e799e06250ce2e618367b166b0d4","name":"https://git.kernel.org/stable/c/25f744ffa0c8e799e06250ce2e618367b166b0d4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/60283726f2845bd78b95efbd0e50b93944780477","name":"https://git.kernel.org/stable/c/60283726f2845bd78b95efbd0e50b93944780477","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6b542d116acecb83a1ca34e8eace304cff6a4ec9","name":"https://git.kernel.org/stable/c/6b542d116acecb83a1ca34e8eace304cff6a4ec9","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-68093","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68093","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 774c47f1d78e373a6bd2964f4e278d1ce26c21cb 60283726f2845bd78b95efbd0e50b93944780477 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 774c47f1d78e373a6bd2964f4e278d1ce26c21cb 7508916b4b55d6f5ecc68cd09774dabd3a6b4440 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 774c47f1d78e373a6bd2964f4e278d1ce26c21cb 0f33b1c457c2199ed130b92cc2ff363a3f7b9415 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 774c47f1d78e373a6bd2964f4e278d1ce26c21cb 6b542d116acecb83a1ca34e8eace304cff6a4ec9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 774c47f1d78e373a6bd2964f4e278d1ce26c21cb 25f744ffa0c8e799e06250ce2e618367b166b0d4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2.6.21","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 2.6.21 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.148 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.101 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.42 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.6 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc4 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["arch/x86/kvm/svm/svm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"60283726f2845bd78b95efbd0e50b93944780477","status":"affected","version":"774c47f1d78e373a6bd2964f4e278d1ce26c21cb","versionType":"git"},{"lessThan":"7508916b4b55d6f5ecc68cd09774dabd3a6b4440","status":"affected","version":"774c47f1d78e373a6bd2964f4e278d1ce26c21cb","versionType":"git"},{"lessThan":"0f33b1c457c2199ed130b92cc2ff363a3f7b9415","status":"affected","version":"774c47f1d78e373a6bd2964f4e278d1ce26c21cb","versionType":"git"},{"lessThan":"6b542d116acecb83a1ca34e8eace304cff6a4ec9","status":"affected","version":"774c47f1d78e373a6bd2964f4e278d1ce26c21cb","versionType":"git"},{"lessThan":"25f744ffa0c8e799e06250ce2e618367b166b0d4","status":"affected","version":"774c47f1d78e373a6bd2964f4e278d1ce26c21cb","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["arch/x86/kvm/svm/svm.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"2.6.21"},{"lessThan":"2.6.21","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.148","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.101","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.42","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc4","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.148","versionStartIncluding":"2.6.21","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.101","versionStartIncluding":"2.6.21","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.42","versionStartIncluding":"2.6.21","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.6","versionStartIncluding":"2.6.21","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc4","versionStartIncluding":"2.6.21","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Bump asid_generation on CPU online to avoid ASID collision after hotplug\n\nIf a vCPU stays scheduled out (or blocked) while the last pCPU it ran\non goes through a hotplug cycle (online->offline->online), and the vCPU\nthen resumes execution on the same pCPU, then it is possible for it to\nrun with an ASID that has now been assigned to a different vCPU,\nresulting in stale TLB translations being used.\n\nsvm_enable_virtualization_cpu() resets asid_generation to 1 and sets\nnext_asid to max_asid + 1 on every CPU online event, including hotplug\ncycles.  Because next_asid starts beyond the pool boundary, the first\ncall to new_asid() after an online event always wraps the pool,\nincrementing asid_generation to 2 and assigning ASIDs starting from\nmin_asid.\n\nConsider two vCPUs from different VMs, vCPU-A pinned to CPU-X holding\nasid_generation=2 and ASID=N from before the hotplug event:\n\n  1. CPU-X goes offline and back online: asid_generation resets to 1,\n     next_asid = max_asid + 1.\n\n  2. One or more vCPUs migrate to CPU-X and call new_asid(), wrapping\n     the pool and consuming ASIDs starting from min_asid.  Eventually\n     vCPU-B from a different VM is assigned asid_generation=2, ASID=N\n     — the same ASID that vCPU-A held before the hotplug.\n\n  3. vCPU-A enters pre_svm_run() on CPU-X: current_vmcb->cpu is\n     unchanged so the migration branch is skipped.  Its saved\n     asid_generation=2 matches sd->asid_generation=2, so the generation\n     check silently passes and vCPU-A continues running with ASID=N —\n     the same ASID just freshly assigned to vCPU-B.\n\nBoth vCPUs from different VMs now run on CPU-X with the same ASID,\ncausing them to share NPT TLB entries and producing stale translations.\n\nThe collision manifests as a KVM internal error (Suberror: 1, emulation\nfailure).  The NPT page fault reports a faulting GPA far outside the\nVM's physical memory range — a sign of stale TLB translations being\nused.  KVM falls back to instruction emulation, which fails on\nFPU/XSave instructions (XRSTOR, STMXCSR) that the emulator does not\nimplement.\n\nFix this by incrementing asid_generation instead of resetting it to 1\nin svm_enable_virtualization_cpu().  On module load, asid_generation\nstarts at 0 (memset) and the increment produces 1, identical to the\nold behaviour.  On subsequent hotplug cycles the generation advances\nbeyond any value a vCPU previously observed on this CPU, so the\ngeneration check in pre_svm_run() reliably forces new_asid() on every\nvCPU after every hotplug cycle."}],"providerMetadata":{"dateUpdated":"2026-08-10T11:58:05.933Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/60283726f2845bd78b95efbd0e50b93944780477"},{"url":"https://git.kernel.org/stable/c/7508916b4b55d6f5ecc68cd09774dabd3a6b4440"},{"url":"https://git.kernel.org/stable/c/0f33b1c457c2199ed130b92cc2ff363a3f7b9415"},{"url":"https://git.kernel.org/stable/c/6b542d116acecb83a1ca34e8eace304cff6a4ec9"},{"url":"https://git.kernel.org/stable/c/25f744ffa0c8e799e06250ce2e618367b166b0d4"}],"title":"KVM: SVM: Bump asid_generation on CPU online to avoid ASID collision after hotplug","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-68093","datePublished":"2026-08-10T11:58:05.933Z","dateReserved":"2026-07-30T09:28:09.367Z","dateUpdated":"2026-08-10T11:58:05.933Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-08-10 13:19:53","lastModifiedDate":"2026-08-10 13:19:53","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"68093","Ordinal":"1","Title":"KVM: SVM: Bump asid_generation on CPU online to avoid ASID colli","CVE":"CVE-2026-68093","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"68093","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Bump asid_generation on CPU online to avoid ASID collision after hotplug\n\nIf a vCPU stays scheduled out (or blocked) while the last pCPU it ran\non goes through a hotplug cycle (online->offline->online), and the vCPU\nthen resumes execution on the same pCPU, then it is possible for it to\nrun with an ASID that has now been assigned to a different vCPU,\nresulting in stale TLB translations being used.\n\nsvm_enable_virtualization_cpu() resets asid_generation to 1 and sets\nnext_asid to max_asid + 1 on every CPU online event, including hotplug\ncycles.  Because next_asid starts beyond the pool boundary, the first\ncall to new_asid() after an online event always wraps the pool,\nincrementing asid_generation to 2 and assigning ASIDs starting from\nmin_asid.\n\nConsider two vCPUs from different VMs, vCPU-A pinned to CPU-X holding\nasid_generation=2 and ASID=N from before the hotplug event:\n\n  1. CPU-X goes offline and back online: asid_generation resets to 1,\n     next_asid = max_asid + 1.\n\n  2. One or more vCPUs migrate to CPU-X and call new_asid(), wrapping\n     the pool and consuming ASIDs starting from min_asid.  Eventually\n     vCPU-B from a different VM is assigned asid_generation=2, ASID=N\n     — the same ASID that vCPU-A held before the hotplug.\n\n  3. vCPU-A enters pre_svm_run() on CPU-X: current_vmcb->cpu is\n     unchanged so the migration branch is skipped.  Its saved\n     asid_generation=2 matches sd->asid_generation=2, so the generation\n     check silently passes and vCPU-A continues running with ASID=N —\n     the same ASID just freshly assigned to vCPU-B.\n\nBoth vCPUs from different VMs now run on CPU-X with the same ASID,\ncausing them to share NPT TLB entries and producing stale translations.\n\nThe collision manifests as a KVM internal error (Suberror: 1, emulation\nfailure).  The NPT page fault reports a faulting GPA far outside the\nVM's physical memory range — a sign of stale TLB translations being\nused.  KVM falls back to instruction emulation, which fails on\nFPU/XSave instructions (XRSTOR, STMXCSR) that the emulator does not\nimplement.\n\nFix this by incrementing asid_generation instead of resetting it to 1\nin svm_enable_virtualization_cpu().  On module load, asid_generation\nstarts at 0 (memset) and the increment produces 1, identical to the\nold behaviour.  On subsequent hotplug cycles the generation advances\nbeyond any value a vCPU previously observed on this CPU, so the\ngeneration check in pre_svm_run() reliably forces new_asid() on every\nvCPU after every hotplug cycle.","Type":"Description","Title":"KVM: SVM: Bump asid_generation on CPU online to avoid ASID colli"}]}}}