CVE-2026-74703 (GCVE-0-2026-74703)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:33 – Updated: 2026-08-25 05:41
VLAI
Title
vhost-scsi: Validate T10 PI scatterlist counts
Summary
In the Linux kernel, the following vulnerability has been resolved: vhost-scsi: Validate T10 PI scatterlist counts When T10 PI is negotiated, vhost-scsi splits protection bytes from the data iterator before mapping the request scatterlists. A malformed request can claim protection bytes that cover or exceed the full payload length. The former leaves no data bytes to map, while the latter underflows exp_data_len before advancing the iterator. Both cases can let a zero data SGL count reach sg_alloc_table_chained(), which triggers BUG_ON(!nents). Reject protection lengths that cover or exceed the payload before subtracting prot_bytes and advancing the iterator. Also propagate negative errors from the protection SGL calculation before calling the allocator, matching the data SGL path.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: bca939d5bcd00d6faea99c47eafd60bed573ef03 , < 2417a498cf3fe64d06faf87e236eda98dd4f04e0 (git)
Affected: bca939d5bcd00d6faea99c47eafd60bed573ef03 , < f8fe3f8d342da750dd10361bf66009fd3072926b (git)
Affected: bca939d5bcd00d6faea99c47eafd60bed573ef03 , < d876c493fc4b811941bfeb4c80beb2dfc4bf025e (git)
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Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.45 , ≤ 6.18.* (semver)
Unaffected: 7.1.9 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/vhost/scsi.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2417a498cf3fe64d06faf87e236eda98dd4f04e0",
              "status": "affected",
              "version": "bca939d5bcd00d6faea99c47eafd60bed573ef03",
              "versionType": "git"
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              "versionType": "git"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.45",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "7.1.9",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvhost-scsi: Validate T10 PI scatterlist counts\n\nWhen T10 PI is negotiated, vhost-scsi splits protection bytes from\nthe data iterator before mapping the request scatterlists. A malformed\nrequest can claim protection bytes that cover or exceed the full payload\nlength. The former leaves no data bytes to map, while the latter\nunderflows exp_data_len before advancing the iterator. Both cases can let\na zero data SGL count reach sg_alloc_table_chained(), which triggers\nBUG_ON(!nents).\n\nReject protection lengths that cover or exceed the payload before\nsubtracting prot_bytes and advancing the iterator. Also propagate\nnegative errors from the protection SGL calculation before calling the\nallocator, matching the data SGL path."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - A malicious KVM guest reaches vhost_scsi_handle_vq() by kicking the virtio-scsi I/O virtqueue; vhost_get_vq_desc() and copy_from_iter_full() pull a guest-controlled virtio_scsi_cmd_req_pi header into the host kernel, not via any network-facing protocol.\nAC:L - With VIRTIO_SCSI_F_T10_PI negotiated, the guest fully controls pi_bytesout/pi_bytesin and descriptor payload sizes; setting protection bytes to cover or exceed the payload deterministically leaves zero data SGL entries and hits BUG_ON(!nents) without races or uncontrollable memory layout.\nPR:N - No host root or capabilities are required; a malicious VM tenant only needs code execution inside a guest with an active virtio-scsi/vhost-scsi endpoint (standard QEMU/KVM+LIO passthrough), matching other guest-to-host virtio/KVM CNA scores for cloud multi-tenant hosts.\nUI:N - No separate victim action is needed; the attacker submits crafted virtio-scsi requests and kicks the virtqueue from their own guest workload without requiring a host administrator or another user to mount storage or perform any interactive step.\nS:C - Guest-supplied virtio-scsi T10 PI requests trigger BUG_ON(!nents) in host sg_alloc_table_chained() during vhost_scsi_mapal(), panicking the physical host kernel and crossing the KVM guest-to-host virtualization security boundary.\nC:N - The failure mode is an explicit BUG_ON(!nents) on zero scatterlist count; there is no demonstrated out-of-bounds read, use-after-free, or other memory corruption before the panic that could disclose host kernel data.\nI:N - No guest-controlled host memory write or control-flow hijack occurs; the host kernel aborts via BUG_ON before target_submit_prep(), and the bug is invalid scatterlist accounting rather than exploitable heap corruption.\nA:H - BUG_ON(!nents) in sg_alloc_table_chained() provokes a host kernel oops/panic in the vhost worker during guest virtio-scsi I/O, denying availability of the hypervisor and all co-resident VMs; the attack is reliably repeatable with crafted PI headers."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-25T05:41:46.287Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2417a498cf3fe64d06faf87e236eda98dd4f04e0"
        },
        {
          "url": "https://git.kernel.org/stable/c/f8fe3f8d342da750dd10361bf66009fd3072926b"
        },
        {
          "url": "https://git.kernel.org/stable/c/d876c493fc4b811941bfeb4c80beb2dfc4bf025e"
        }
      ],
      "title": "vhost-scsi: Validate T10 PI scatterlist counts",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74703",
    "datePublished": "2026-08-22T15:33:02.872Z",
    "dateReserved": "2026-08-15T05:44:03.927Z",
    "dateUpdated": "2026-08-25T05:41:46.287Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74703",
      "date": "2026-09-01",
      "epss": "0.00137",
      "percentile": "0.0341"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74703\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-22T16:16:44.983\",\"lastModified\":\"2026-08-25T06:18:54.330\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nvhost-scsi: Validate T10 PI scatterlist counts\\n\\nWhen T10 PI is negotiated, vhost-scsi splits protection bytes from\\nthe data iterator before mapping the request scatterlists. A malformed\\nrequest can claim protection bytes that cover or exceed the full payload\\nlength. The former leaves no data bytes to map, while the latter\\nunderflows exp_data_len before advancing the iterator. Both cases can let\\na zero data SGL count reach sg_alloc_table_chained(), which triggers\\nBUG_ON(!nents).\\n\\nReject protection lengths that cover or exceed the payload before\\nsubtracting prot_bytes and advancing the iterator. Also propagate\\nnegative errors from the protection SGL calculation before calling the\\nallocator, matching the data SGL path.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/vhost/scsi.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"bca939d5bcd00d6faea99c47eafd60bed573ef03\",\"lessThan\":\"2417a498cf3fe64d06faf87e236eda98dd4f04e0\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"bca939d5bcd00d6faea99c47eafd60bed573ef03\",\"lessThan\":\"f8fe3f8d342da750dd10361bf66009fd3072926b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"bca939d5bcd00d6faea99c47eafd60bed573ef03\",\"lessThan\":\"d876c493fc4b811941bfeb4c80beb2dfc4bf025e\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/vhost/scsi.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.15\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.15\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.45\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.9\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"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:N/UI:N/S:C/C:N/I:N/A:H\",\"baseScore\":7.1,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.5,\"impactScore\":4.0}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/2417a498cf3fe64d06faf87e236eda98dd4f04e0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d876c493fc4b811941bfeb4c80beb2dfc4bf025e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f8fe3f8d342da750dd10361bf66009fd3072926b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-25T08:55:00+00:00",
      "cve": "CVE-2026-74703",
      "id": "CVE-2026-74703",
      "initial_release_date": "2026-08-22T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: vhost-scsi: Validate T10 PI scatterlist counts",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74703.json",
      "version": "3"
    }
  }
}



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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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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.


Detection rules are retrieved from Rulezet.