{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-68093", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-30T09:28:09.367Z", "datePublished": "2026-08-10T11:58:05.933Z", "dateUpdated": "2026-08-19T16:29:15.060Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-19T16:29:15.060Z" }, "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." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/x86/kvm/svm/svm.c" ], "versions": [ { "version": "774c47f1d78e373a6bd2964f4e278d1ce26c21cb", "lessThan": "2028b81321dc757b6875b99c10d908e349c141e2", "status": "affected", "versionType": "git" }, { "version": "774c47f1d78e373a6bd2964f4e278d1ce26c21cb", "lessThan": "60283726f2845bd78b95efbd0e50b93944780477", "status": "affected", "versionType": "git" }, { "version": "774c47f1d78e373a6bd2964f4e278d1ce26c21cb", "lessThan": "7508916b4b55d6f5ecc68cd09774dabd3a6b4440", "status": "affected", "versionType": "git" }, { "version": "774c47f1d78e373a6bd2964f4e278d1ce26c21cb", "lessThan": "0f33b1c457c2199ed130b92cc2ff363a3f7b9415", "status": "affected", "versionType": "git" }, { "version": "774c47f1d78e373a6bd2964f4e278d1ce26c21cb", "lessThan": "6b542d116acecb83a1ca34e8eace304cff6a4ec9", "status": "affected", "versionType": "git" }, { "version": "774c47f1d78e373a6bd2964f4e278d1ce26c21cb", "lessThan": "25f744ffa0c8e799e06250ce2e618367b166b0d4", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/x86/kvm/svm/svm.c" ], "versions": [ { "version": "2.6.21", "status": "affected" }, { "version": "0", "lessThan": "2.6.21", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.183", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.148", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.101", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.42", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.6", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.21", "versionEndExcluding": "6.1.183" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.21", "versionEndExcluding": "6.6.148" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.21", "versionEndExcluding": "6.12.101" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.21", "versionEndExcluding": "6.18.42" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.21", "versionEndExcluding": "7.1.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.21", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/2028b81321dc757b6875b99c10d908e349c141e2" }, { "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" } } } }