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CVE-2026-80921 (GCVE-0-2026-80921)

Vulnerability from cvelistv5 – Published: 2026-09-09 16:19 – Updated: 2026-09-10 05:50
VLAI
Title
KVM: s390: vsie: zero stale crypto bits
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: vsie: zero stale crypto bits When shadowing crypto access bits from a format0 apcb (crycb 0 or 1), the bits 64..255 are unchanged from whatever is in the vsie page in the crycb and thus in the apcb. This gives a nested guest potential access to a device no longer available. Zero out the remaining bits.
Severity
8.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < d110b3297f11ef227098b8a82ade2d5f123b7d2f (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < 59d51550b5cb916bda037673a721a404b3b47a0d (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < f6079dca67eccb5eabef9f72437948c66dc5131f (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < 087c19cc60a8caa1a08e1e434c8be2caf6c27733 (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < 7d23489f51109e3ebba5b5db8c5f0185af7b7fdf (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < 935eeba276012916c76243e5cbb843efd8fdb75d (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < d4bcd2df6d0d2af916b4fe1a533958778ea7c45b (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < 29b4f7bc2991313bd3e6f6fb8fdf1b173f086dd6 (git)
Affected: 6b79de4b056e5a2febc0c61233d8f0ad7868e49c , < 34d5b5b646c91cfb9338d7a12c955a70ffb8c66b (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.20
Unaffected: 0 , < 4.20 (semver)
Unaffected: 5.10.269 , ≤ 5.10.* (semver)
Unaffected: 5.15.220 , ≤ 5.15.* (semver)
Unaffected: 6.1.187 , ≤ 6.1.* (semver)
Unaffected: 6.6.156 , ≤ 6.6.* (semver)
Unaffected: 6.12.108 , ≤ 6.12.* (semver)
Unaffected: 6.18.49 , ≤ 6.18.* (semver)
Unaffected: 7.1.13 , ≤ 7.1.* (semver)
Unaffected: 7.2.3 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
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              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
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      "descriptions": [
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          "lang": "en",
          "value": "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."
        }
      ],
      "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\u0027s 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"
      },
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          "url": "https://git.kernel.org/stable/c/d110b3297f11ef227098b8a82ade2d5f123b7d2f"
        },
        {
          "url": "https://git.kernel.org/stable/c/59d51550b5cb916bda037673a721a404b3b47a0d"
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        {
          "url": "https://git.kernel.org/stable/c/34d5b5b646c91cfb9338d7a12c955a70ffb8c66b"
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      ],
      "title": "KVM: s390: vsie: zero stale crypto bits",
      "x_generator": {
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    "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"
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      "cve": "CVE-2026-80921",
      "date": "2026-09-11",
      "epss": "0.00126",
      "percentile": "0.02574"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-11T01:02:22.000Z",
      "cve": "CVE-2026-80921",
      "id": "msrc_CVE-2026-80921",
      "initial_release_date": "2026-09-11T01:02:22.000Z",
      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "KVM: s390: vsie: zero stale crypto bits",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-80921.json",
      "version": "1"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-80921\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-09-09T17:17:47.240\",\"lastModified\":\"2026-09-10T06:17:06.037\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"arch/s390/kvm/vsie.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"d110b3297f11ef227098b8a82ade2d5f123b7d2f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"59d51550b5cb916bda037673a721a404b3b47a0d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"f6079dca67eccb5eabef9f72437948c66dc5131f\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"087c19cc60a8caa1a08e1e434c8be2caf6c27733\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"7d23489f51109e3ebba5b5db8c5f0185af7b7fdf\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"935eeba276012916c76243e5cbb843efd8fdb75d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"d4bcd2df6d0d2af916b4fe1a533958778ea7c45b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"29b4f7bc2991313bd3e6f6fb8fdf1b173f086dd6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6b79de4b056e5a2febc0c61233d8f0ad7868e49c\",\"lessThan\":\"34d5b5b646c91cfb9338d7a12c955a70ffb8c66b\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"arch/s390/kvm/vsie.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.20\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.20\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.269\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.220\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.187\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.156\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.108\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.49\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.13\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2.3\",\"lessThanOrEqual\":\"7.2.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.3-rc1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"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\":2.0,\"impactScore\":6.0}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/087c19cc60a8caa1a08e1e434c8be2caf6c27733\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/29b4f7bc2991313bd3e6f6fb8fdf1b173f086dd6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/34d5b5b646c91cfb9338d7a12c955a70ffb8c66b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/59d51550b5cb916bda037673a721a404b3b47a0d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/7d23489f51109e3ebba5b5db8c5f0185af7b7fdf\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/935eeba276012916c76243e5cbb843efd8fdb75d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d110b3297f11ef227098b8a82ade2d5f123b7d2f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d4bcd2df6d0d2af916b4fe1a533958778ea7c45b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f6079dca67eccb5eabef9f72437948c66dc5131f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.