CVE-2026-89920 (GCVE-0-2026-89920)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:32 – Updated: 2026-10-30 12:33
VLAI
Title
KVM: s390: Fix memory corruption by not reinjecting CK machine checks
Summary
In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix memory corruption by not reinjecting CK machine checks Channel-subsystem damage machine checks are for the host channel subsystem. The guest channel subsystem is emulated in the userspace VMM. There is no point in forwarding such machine checks into the guest. This also simplifies the machine check reinjection and avoids kfree of a stack variable as reported by sashiko. There might be still machine checks that have the ck bit set with another bit (like instruction damage), mask out the CK bit in s390_backup_mcck_info(), like the CP and ED bits already are.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6971 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 4d62fcc0b692e3b4058d7d138114c27cd8b011f7 , < 045f3e95a0deccb277c29bd003e1d43c0ad40c90 (git)
Affected: 4d62fcc0b692e3b4058d7d138114c27cd8b011f7 , < 5c63e2ed840c85e27172ab78e7db3ac77fba281b (git)
Affected: 4d62fcc0b692e3b4058d7d138114c27cd8b011f7 , < b7631982fb65dd355acd18e62b384bc8125e9c44 (git)
Affected: 4d62fcc0b692e3b4058d7d138114c27cd8b011f7 , < 6ee52d3af2a1bf70349cf3f860933c8d221e229a (git)
Affected: 4d62fcc0b692e3b4058d7d138114c27cd8b011f7 , < 7077ec953996acc04b49d1dfc43df1c1a2a74395 (git)
Affected: 4d62fcc0b692e3b4058d7d138114c27cd8b011f7 , < 546dde823a36d7283dcf46127c2f3d093443860f (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.13
Unaffected: 0 , < 4.13 (semver)
Unaffected: 6.1.191 , ≤ 6.1.* (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.114 , ≤ 6.12.* (semver)
Unaffected: 6.18.51 , ≤ 6.18.* (semver)
Unaffected: 7.2.5 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/s390/include/asm/nmi.h",
            "arch/s390/kernel/nmi.c",
            "arch/s390/kvm/interrupt.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "045f3e95a0deccb277c29bd003e1d43c0ad40c90",
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "versionType": "git"
            },
            {
              "lessThan": "5c63e2ed840c85e27172ab78e7db3ac77fba281b",
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "versionType": "git"
            },
            {
              "lessThan": "b7631982fb65dd355acd18e62b384bc8125e9c44",
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "versionType": "git"
            },
            {
              "lessThan": "6ee52d3af2a1bf70349cf3f860933c8d221e229a",
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "versionType": "git"
            },
            {
              "lessThan": "7077ec953996acc04b49d1dfc43df1c1a2a74395",
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "versionType": "git"
            },
            {
              "lessThan": "546dde823a36d7283dcf46127c2f3d093443860f",
              "status": "affected",
              "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/s390/include/asm/nmi.h",
            "arch/s390/kernel/nmi.c",
            "arch/s390/kvm/interrupt.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.13"
            },
            {
              "lessThan": "4.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.191",
                  "versionStartIncluding": "4.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "4.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.114",
                  "versionStartIncluding": "4.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.51",
                  "versionStartIncluding": "4.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "4.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "4.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Fix memory corruption by not reinjecting CK machine checks\n\nChannel-subsystem damage machine checks are for the host channel\nsubsystem. The guest channel subsystem is emulated in the userspace VMM.\nThere is no point in forwarding such machine checks into the guest.\n\nThis also simplifies the machine check reinjection and avoids kfree of a\nstack variable as reported by sashiko.  There might be still machine\nchecks that have the ck bit set with another bit (like instruction\ndamage), mask out the CK bit in s390_backup_mcck_info(), like the CP and\nED bits already are."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - Reached only after a local KVM_RUN puts an s390 vCPU in SIE (kvm_arch_vcpu_ioctl_run -\u003e __vcpu_run -\u003e kvm_s390_enter_exit_sie/sie64a, also vsie). A host CK machine check then hits vcpu_post_run -\u003e kvm_s390_reinject_machine_check. No network or physical path.\nAC:H - The CK bit comes from host lowcore via s390_backup_mcck_info(), not guest or ioctl input. Channel-subsystem damage is a host CSS hardware/firmware condition the attacker cannot induce; guest CSS is emulated in userspace and does not drive the host CSS.\nPR:L - KVM_CREATE_VM and KVM_RUN have no capable() check for ordinary (non-ucontrol) VMs. A kvm-group user who can open /dev/kvm, or a tenant already running in an s390 KVM guest, suffices; host init-namespace root is not required.\nUI:N - The attacker issues KVM_RUN on a vCPU they created, or a tenant guest is already in SIE. No separate victim action such as mounting a filesystem, opening a file, or attaching a device is required.\nS:C - kvm_s390_reinject_machine_check runs in the host kernel on the SIE-exit path and kfree()s a stack object, corrupting host allocator state. That crosses the KVM guest-to-hypervisor boundary and can compromise the host and co-located VMs.\nC:H - kfree() of the on-stack kvm_s390_interrupt_info treats a kernel stack address as a slab or large-kmalloc object (page_slab/free_large_kmalloc/slab_free), corrupting allocator metadata. That host-kernel memory corruption can be leveraged for disclosure.\nI:H - The same invalid free corrupts SLUB or page-allocator metadata, which can be turned into an arbitrary host write or control-flow hijack. CNA guidance scores this class of kernel memory corruption as High integrity.\nA:H - kfree of a non-slab stack address hits WARN_ON_ONCE in free_large_kmalloc or slab_free on a bogus object and oopses or panics the host kernel, denying service to the hypervisor and every co-located VM."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-30T12:33:25.963Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/045f3e95a0deccb277c29bd003e1d43c0ad40c90"
        },
        {
          "url": "https://git.kernel.org/stable/c/5c63e2ed840c85e27172ab78e7db3ac77fba281b"
        },
        {
          "url": "https://git.kernel.org/stable/c/b7631982fb65dd355acd18e62b384bc8125e9c44"
        },
        {
          "url": "https://git.kernel.org/stable/c/6ee52d3af2a1bf70349cf3f860933c8d221e229a"
        },
        {
          "url": "https://git.kernel.org/stable/c/7077ec953996acc04b49d1dfc43df1c1a2a74395"
        },
        {
          "url": "https://git.kernel.org/stable/c/546dde823a36d7283dcf46127c2f3d093443860f"
        }
      ],
      "title": "KVM: s390: Fix memory corruption by not reinjecting CK machine checks",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89920",
    "datePublished": "2026-09-16T10:32:14.735Z",
    "dateReserved": "2026-09-11T19:38:34.775Z",
    "dateUpdated": "2026-10-30T12:33:25.963Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-89920",
      "date": "2026-11-02",
      "epss": "0.00176",
      "percentile": "0.07041"
    },
    "microsoft_vex": {
      "current_release_date": "2026-11-01T14:45:05.000Z",
      "cve": "CVE-2026-89920",
      "id": "msrc_CVE-2026-89920",
      "initial_release_date": "2026-09-17T01:14:29.000Z",
      "product_status:known_affected": "4",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "KVM: s390: Fix memory corruption by not reinjecting CK machine checks",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-89920.json",
      "version": "6"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "arch/s390/include/asm/nmi.h",
                  "arch/s390/kernel/nmi.c",
                  "arch/s390/kvm/interrupt.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "lessThan": "045f3e95a0deccb277c29bd003e1d43c0ad40c90",
                    "status": "affected",
                    "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "5c63e2ed840c85e27172ab78e7db3ac77fba281b",
                    "status": "affected",
                    "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "b7631982fb65dd355acd18e62b384bc8125e9c44",
                    "status": "affected",
                    "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "6ee52d3af2a1bf70349cf3f860933c8d221e229a",
                    "status": "affected",
                    "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "7077ec953996acc04b49d1dfc43df1c1a2a74395",
                    "status": "affected",
                    "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
                    "versionType": "git"
                  },
                  {
                    "lessThan": "546dde823a36d7283dcf46127c2f3d093443860f",
                    "status": "affected",
                    "version": "4d62fcc0b692e3b4058d7d138114c27cd8b011f7",
                    "versionType": "git"
                  }
                ]
              },
              {
                "defaultStatus": "affected",
                "product": "Linux",
                "programFiles": [
                  "arch/s390/include/asm/nmi.h",
                  "arch/s390/kernel/nmi.c",
                  "arch/s390/kvm/interrupt.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
                    "status": "affected",
                    "version": "4.13"
                  },
                  {
                    "lessThan": "4.13",
                    "status": "unaffected",
                    "version": "0",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.1.*",
                    "status": "unaffected",
                    "version": "6.1.191",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.6.*",
                    "status": "unaffected",
                    "version": "6.6.160",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.12.*",
                    "status": "unaffected",
                    "version": "6.12.114",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "6.18.*",
                    "status": "unaffected",
                    "version": "6.18.51",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "7.2.*",
                    "status": "unaffected",
                    "version": "7.2.5",
                    "versionType": "semver"
                  },
                  {
                    "lessThanOrEqual": "*",
                    "status": "unaffected",
                    "version": "7.3",
                    "versionType": "original_commit_for_fix"
                  }
                ]
              }
            ],
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: s390: Fix memory corruption by not reinjecting CK machine checks\n\nChannel-subsystem damage machine checks are for the host channel\nsubsystem. The guest channel subsystem is emulated in the userspace VMM.\nThere is no point in forwarding such machine checks into the guest.\n\nThis also simplifies the machine check reinjection and avoids kfree of a\nstack variable as reported by sashiko.  There might be still machine\nchecks that have the ck bit set with another bit (like instruction\ndamage), mask out the CK bit in s390_backup_mcck_info(), like the CP and\nED bits already are."
          }
        ],
        "id": "CVE-2026-89920",
        "lastModified": "2026-10-30T13:20:35.690",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "HIGH",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "CHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
                "version": "3.1"
              },
              "exploitabilityScore": 1.1,
              "impactScore": 6.0,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-09-16T11:17:01.073",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/045f3e95a0deccb277c29bd003e1d43c0ad40c90"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/546dde823a36d7283dcf46127c2f3d093443860f"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/5c63e2ed840c85e27172ab78e7db3ac77fba281b"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/6ee52d3af2a1bf70349cf3f860933c8d221e229a"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/7077ec953996acc04b49d1dfc43df1c1a2a74395"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/b7631982fb65dd355acd18e62b384bc8125e9c44"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-30T15:11:35+00:00",
      "cve": "CVE-2026-89920",
      "id": "CVE-2026-89920",
      "initial_release_date": "2026-09-16T00:00:00+00:00",
      "product_status:known_affected": "251",
      "product_status:known_not_affected": "28",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: KVM: s390: Fix memory corruption by not reinjecting CK machine checks",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89920.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-10-20T00:55:01Z",
      "cve": "CVE-2026-89920",
      "id": "CVE-2026-89920",
      "initial_release_date": "2026-09-17T16:34:50Z",
      "product_status:known_affected": "255",
      "product_status:known_not_affected": "93",
      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-89920",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-89920.json",
      "version": "5"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

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.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • 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.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.