CVE-2026-90009 (GCVE-0-2026-90009)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:33 – Updated: 2026-10-19 08:56
VLAI
Title
scsi: bsg: Fix TOCTOU in io_uring passthrough command setup
Summary
In the Linux kernel, the following vulnerability has been resolved: scsi: bsg: Fix TOCTOU in io_uring passthrough command setup scsi_bsg_uring_cmd() reads bsg_uring_cmd from the shared mmap'd SQE. Userspace can change a field after we check it and before we use it. request_len is the sharp case: it can grow past sizeof(scmd->cmnd) after the bound check and overflow scmd->cmnd in copy_from_user(). READ_ONCE() the SQE fields we check or use into locals before use.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6639 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7b6d3255e7f8c6df2d21504c47808e3ce84649ac , < f033530105aa73d82c121d54b57f358e4865d2f4 (git)
Affected: 7b6d3255e7f8c6df2d21504c47808e3ce84649ac , < 4b3c5965fca99f62d31c963294bd5b23cc488e97 (git)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 7.2.5 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/scsi/scsi_bsg.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f033530105aa73d82c121d54b57f358e4865d2f4",
              "status": "affected",
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              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
            }
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        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.5",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
            }
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nscsi: bsg: Fix TOCTOU in io_uring passthrough command setup\n\nscsi_bsg_uring_cmd() reads bsg_uring_cmd from the shared mmap\u0027d SQE.\nUserspace can change a field after we check it and before we use it.\nrequest_len is the sharp case: it can grow past sizeof(scmd-\u003ecmnd) after\nthe bound check and overflow scmd-\u003ecmnd in copy_from_user().\n\nREAD_ONCE() the SQE fields we check or use into locals before use."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - scsi_bsg_uring_cmd() is reached only via a local io_uring IORING_OP_URING_CMD on a SCSI BSG device node (/dev/bsg/\u003ch:c:i:l\u003e); io_uring and BSG are local syscall/device paths, not a network protocol handler.\nAC:L - The attacker owns both sides of the TOCTOU: one thread submits the uring_cmd while another rewrites request_len in the shared mmap\u0027d SQE. The inline issue path never copies the SQE first, and scsi_alloc_request() sits between the bound check and copy_from_user, making the race attacker-driven and retryable.\nPR:L - bsg_open() has no capability check; access is only DAC on /dev/bsg/* for ordinary SCSI devices. scsi_cmd_allowed() runs after the overflow. Disk/cdrom group membership and uaccess on removable SCSI/USB devices grant this to unprivileged local users without init-namespace root.\nUI:N - The attacker opens the BSG node, creates an io_uring ring with SQE128/CQE32, and submits the racing passthrough command themselves; no victim action is required.\nS:U - The overflow corrupts the blk-mq scsi_cmnd PDU and adjacent kernel heap in the same host kernel security authority, enabling local privilege escalation rather than a VM, IOMMU, or sandbox boundary crossing.\nC:H - copy_from_user() overflows the 32-byte scmd-\u003ecmnd into scsi_cmnd pointer fields (sdb, sense_buffer, host_scribble) and adjacent heap with attacker-controlled bytes, which can be groomed into kernel memory disclosure.\nI:H - The same attacker-controlled heap overflow overwrites kernel pointers and adjacent blk-mq request objects, providing a write primitive exploitable for control-flow hijacking and privilege escalation.\nA:H - A large request_len smash or later use of corrupted scsi_cmnd pointers causes a kernel oops or panic; even a failed copy_from_user still writes through kernel memory until a fault, then frees the corrupted request."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:56:23.130Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f033530105aa73d82c121d54b57f358e4865d2f4"
        },
        {
          "url": "https://git.kernel.org/stable/c/4b3c5965fca99f62d31c963294bd5b23cc488e97"
        }
      ],
      "title": "scsi: bsg: Fix TOCTOU in io_uring passthrough command setup",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90009",
    "datePublished": "2026-09-16T10:33:17.446Z",
    "dateReserved": "2026-09-11T19:38:34.781Z",
    "dateUpdated": "2026-10-19T08:56:23.130Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-90009",
      "date": "2026-11-10",
      "epss": "0.00165",
      "percentile": "0.05777"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "defaultStatus": "unaffected",
                "product": "Linux",
                "programFiles": [
                  "drivers/scsi/scsi_bsg.c"
                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
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                    "versionType": "git"
                  },
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                    "lessThan": "4b3c5965fca99f62d31c963294bd5b23cc488e97",
                    "status": "affected",
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                    "versionType": "git"
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              },
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                "defaultStatus": "affected",
                "product": "Linux",
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                ],
                "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                "vendor": "Linux",
                "versions": [
                  {
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                    "version": "7.1"
                  },
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                    "version": "0",
                    "versionType": "semver"
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                    "version": "7.2.5",
                    "versionType": "semver"
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                    "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\nscsi: bsg: Fix TOCTOU in io_uring passthrough command setup\n\nscsi_bsg_uring_cmd() reads bsg_uring_cmd from the shared mmap\u0027d SQE.\nUserspace can change a field after we check it and before we use it.\nrequest_len is the sharp case: it can grow past sizeof(scmd-\u003ecmnd) after\nthe bound check and overflow scmd-\u003ecmnd in copy_from_user().\n\nREAD_ONCE() the SQE fields we check or use into locals before use."
          }
        ],
        "id": "CVE-2026-90009",
        "lastModified": "2026-10-19T09:18:48.710",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
          ]
        },
        "published": "2026-09-16T11:17:13.553",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/4b3c5965fca99f62d31c963294bd5b23cc488e97"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/f033530105aa73d82c121d54b57f358e4865d2f4"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-11-07T11:27:12+00:00",
      "cve": "CVE-2026-90009",
      "id": "CVE-2026-90009",
      "initial_release_date": "2026-09-16T00:00:00+00:00",
      "product_status:known_not_affected": "203",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: scsi: bsg: Fix TOCTOU in io_uring passthrough command setup",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90009.json",
      "version": "3"
    }
  }
}



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