{"api_version":"1","generated_at":"2026-09-10T09:13:03+00:00","cve":"CVE-2026-80921","urls":{"html":"https://cve.report/CVE-2026-80921","api":"https://cve.report/api/cve/CVE-2026-80921.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-80921","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-80921"},"summary":{"title":"KVM: s390: vsie: zero stale crypto bits","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: vsie: zero stale crypto bits\n\nWhen shadowing crypto access bits from a format0 apcb (crycb 0 or 1),\nthe bits 64..255 are unchanged from whatever is in the vsie page in the\ncrycb and thus in the apcb. This gives a nested guest potential access\nto a device no longer available. Zero out the remaining bits.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-09 17:17:47","updated_at":"2026-09-10 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the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: vsie: zero stale crypto bits\n\nWhen shadowing crypto access bits from a format0 apcb (crycb 0 or 1),\nthe bits 64..255 are unchanged from whatever is in the vsie page in the\ncrycb and thus in the apcb. This gives a nested guest potential access\nto a device no longer available. Zero out the remaining bits."}],"metrics":[{"cvssV3_1":{"baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"scenarios":[{"lang":"en","value":"AV:L - The bug is reached when an s390 KVM guest executes the privileged SIE instruction (B2/14), intercepted through handle_instruction() to kvm_s390_handle_vsie() and setup_apcb10(); that is a local guest/KVM ioctl path with no network, Bluetooth, or USB exposure.\nAC:L - An L1 guest that first runs a FORMAT-2 nested SCB (setup_apcb11 fills all 256 APCB bits) and then a FORMAT-0/1 SCB on a recycled vsie page hits setup_apcb10() deterministically; get_vsie_page() reuses pages without clearing crycb, so leftover bits 64-255 persist with no race or uncontrolled memory layout.\nPR:L - SIE requires guest supervisor state, i.e. the tenant guest kernel or an unprivileged host kvm-group user running QEMU, not host root; kvm_s390_handle_vsie() has no host capability gate, and user namespaces cannot substitute for this path, so privileges stay Low rather than High.\nUI:N - The attacker guest issues SIE and uses the over-permissive shadow APCB itself; vsie page reuse and crycb shadowing run automatically inside KVM with no victim mount, click, or other user action.\nS:C - Leftover APCB bits grant a nested guest millicode-enforced access to host AP adapters/domains outside its delegated matrix, crossing the KVM nested-virt and vfio-ap passthrough boundary into another guest's or the host zcrypt authority, equivalent to an IOMMU/device isolation bypass.\nC:H - Unauthorized APQNs let the nested guest issue NQAP/DQAP against queues that may now belong to the host zcrypt stack or another tenant, disclosing cryptographic request/response data and key material on those adapters/domains.\nI:H - The nested guest can enqueue arbitrary AP requests and change hardware queue state on adapters and domains 64-255 that the current shadow should have cleared, corrupting crypto operations the host believes are exclusive to another consumer.\nA:H - With those leftover APQNs the nested guest can PQAP(ZAPQ)-reset or flood shared queues, denying host or sibling-guest crypto services (pkey, secure-key LUKS, openCryptoki) that depend on the same physical adapter/domain."}]}],"providerMetadata":{"dateUpdated":"2026-09-10T05:50:22.520Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/d110b3297f11ef227098b8a82ade2d5f123b7d2f"},{"url":"https://git.kernel.org/stable/c/59d51550b5cb916bda037673a721a404b3b47a0d"},{"url":"https://git.kernel.org/stable/c/f6079dca67eccb5eabef9f72437948c66dc5131f"},{"url":"https://git.kernel.org/stable/c/087c19cc60a8caa1a08e1e434c8be2caf6c27733"},{"url":"https://git.kernel.org/stable/c/7d23489f51109e3ebba5b5db8c5f0185af7b7fdf"},{"url":"https://git.kernel.org/stable/c/935eeba276012916c76243e5cbb843efd8fdb75d"},{"url":"https://git.kernel.org/stable/c/d4bcd2df6d0d2af916b4fe1a533958778ea7c45b"},{"url":"https://git.kernel.org/stable/c/29b4f7bc2991313bd3e6f6fb8fdf1b173f086dd6"},{"url":"https://git.kernel.org/stable/c/34d5b5b646c91cfb9338d7a12c955a70ffb8c66b"}],"title":"KVM: s390: vsie: zero stale crypto bits","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-80921","datePublished":"2026-09-09T16:19:42.335Z","dateReserved":"2026-08-26T14:34:25.801Z","dateUpdated":"2026-09-10T05:50:22.520Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-09 17:17:47","lastModifiedDate":"2026-09-10 06:17:06","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2,"impactScore":6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"80921","Ordinal":"1","Title":"KVM: s390: vsie: zero stale crypto bits","CVE":"CVE-2026-80921","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"80921","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: vsie: zero stale crypto bits\n\nWhen shadowing crypto access bits from a format0 apcb (crycb 0 or 1),\nthe bits 64..255 are unchanged from whatever is in the vsie page in the\ncrycb and thus in the apcb. This gives a nested guest potential access\nto a device no longer available. Zero out the remaining bits.","Type":"Description","Title":"KVM: s390: vsie: zero stale crypto bits"}]}}}