{"id":"AZL-108773","summary":"CVE-2026-98715 affecting package kernel 6.6.157.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: SVM: Preserve TLB control (i.e. pending TLB flush) on failed VMRUN\n\nDon't reset the VMCB's TLB control back to \"do nothing\" on a failed VMRUN,\nas empirical testing shows that the CPU performs the requested TLB flush if\nand only if VMRUN is successful, i.e. clearing TLB control on a failed\nVMRUN effectively drops a TLB flush.\n\nExplicitly track the need to flush all ASIDs on a per-CPU basis, as the\nASID reuse condition is tied to the pCPU, not to the vCPU.  As a bonus,\nthis also obviates the need to avoid clobbering FLUSH_ALL_ASID with\nTLB_CONTROL_FLUSH_ASID, e.g. in svm_flush_tlb_asid().\n\nDeliberately don't bother saving/restoring the \"old\" tlb_ctl on failure,\nin quotes because it's not exactly the old tlb_ctl, it's the tlb_ctl from\nafter pre_svm_run(), but before updating tlb_ctl for flush_all_asids.  If\nVMRUN fails and TLB_CONTROL_FLUSH_ALL_ASID is forced, then the next\nsuccessful run of the VMCB *may* unnecessarily flush all ASIDs, which\nstrictly speaking could result in noisy neighbor issues.  However, the\nfact that new_asid() is already guest-triggerable, because of KVM's flawed\nbehavior of clearing the ASID on emulated INIT, means that a guest can\nalready trigger a flush of all ASIDs at roughly the same rate.  And once\nKVM stops clobbering the ASID on emulated INIT, *or* assigns a static ASID\nto each vCPU, this flaw goes away.","modified":"2026-10-19T14:17:05.728340775Z","published":"2026-10-18T16:17:25Z","upstream":["CVE-2026-98715"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98715"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.157.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-108773.json"}}],"schema_version":"1.9.0"}