CVE-2026-97991 (GCVE-0-2026-97991)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:23 – Updated: 2026-09-25 14:41
VLAI
Title
vdpa_sim_blk: reject out-of-range sector starts
Summary
In the Linux kernel, the following vulnerability has been resolved: vdpa_sim_blk: reject out-of-range sector starts vdpasim_blk_check_range() logs an invalid start sector but continues validating the request. The subsequent unsigned capacity subtraction can underflow and let an out-of-range buffer offset reach the data path. The invalid offset is used by three request paths. VIRTIO_BLK_T_OUT copies guest data to blk->buffer + offset through vringh_iov_pull_iotlb(), causing an out-of-bounds write in _copy_from_iter() or memcpy(). VIRTIO_BLK_T_IN copies from blk->buffer + offset to the guest through vringh_iov_push_iotlb(), causing an out-of-bounds read in _copy_to_iter(). VIRTIO_BLK_T_WRITE_ZEROES passes blk->buffer + offset to memset(), causing an out-of-bounds write. Reject starts at or beyond the capacity before the subtraction. Treat the capacity boundary as invalid because the IN and OUT paths round byte counts down to sectors for validation but later copy the original byte counts. A sub-sector request at the capacity boundary would otherwise still access past the end of the buffer. I found this bug myself, though the patch was written with AI assistance.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7d189f617f83f780915b737896a696ff605bd19f , < 14acb0d44b7d90a077beb7b92b444b90bafda9d9 (git)
Affected: 7d189f617f83f780915b737896a696ff605bd19f , < a8a1413a2cfdbedc896249f461d6d92efbbfe21f (git)
Affected: 7d189f617f83f780915b737896a696ff605bd19f , < d6dac17e20fd2abd0eb8c09d69fccf7426e12bcf (git)
Affected: 7d189f617f83f780915b737896a696ff605bd19f , < 0a8693f00c408d85f086ad85d29e7030bf1e2055 (git)
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Linux Linux Affected: 5.13
Unaffected: 0 , < 5.13 (semver)
Unaffected: 6.12.111 , ≤ 6.12.* (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/vdpa/vdpa_sim/vdpa_sim_blk.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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              "version": "7d189f617f83f780915b737896a696ff605bd19f",
              "versionType": "git"
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              "versionType": "git"
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          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/vdpa/vdpa_sim/vdpa_sim_blk.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.13"
            },
            {
              "lessThan": "5.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.111",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.53",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                },
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                  "versionEndExcluding": "7.3-rc3",
                  "versionStartIncluding": "5.13",
                  "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\nvdpa_sim_blk: reject out-of-range sector starts\n\nvdpasim_blk_check_range() logs an invalid start sector but continues\nvalidating the request.  The subsequent unsigned capacity subtraction can\nunderflow and let an out-of-range buffer offset reach the data path.\n\nThe invalid offset is used by three request paths.  VIRTIO_BLK_T_OUT\ncopies guest data to blk-\u003ebuffer + offset through\nvringh_iov_pull_iotlb(), causing an out-of-bounds write in\n_copy_from_iter() or memcpy().  VIRTIO_BLK_T_IN copies from\nblk-\u003ebuffer + offset to the guest through vringh_iov_push_iotlb(),\ncausing an out-of-bounds read in _copy_to_iter().\nVIRTIO_BLK_T_WRITE_ZEROES passes blk-\u003ebuffer + offset to memset(),\ncausing an out-of-bounds write.\n\nReject starts at or beyond the capacity before the subtraction.  Treat the\ncapacity boundary as invalid because the IN and OUT paths round byte counts\ndown to sectors for validation but later copy the original byte counts.  A\nsub-sector request at the capacity boundary would otherwise still access\npast the end of the buffer.\n\nI found this bug myself, though the patch was written with AI assistance."
        }
      ],
      "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 - The bad value is virtio_blk_outhdr.sector, written into the virtqueue by the virtio driver. That driver is a guest VM using the device through vhost-vdpa, or a local process with access to /dev/vhost-vdpa-N. vdpasim_blk_handle_req() reads it with vringh_getdesc_iotlb()/vringh_iov_pull_iotlb(). No network protocol carries it.\nAC:H - The code needs a vdpa_sim_blk device, a test simulator that root must create with VDPA_CMD_DEV_NEW (GENL_ADMIN_PERM) and bind to vhost-vdpa for a VM. The attacker cannot set that up. Once it exists, a single request with a large sector fires the bug every time.\nPR:L - The attacker needs control of the virtqueue driver, for example the guest kernel of a VM that was given the device, or a user granted the vhost-vdpa char device. That is ordinary tenant privilege, not host root.\nUI:N - Once the device is assigned, the attacker posts the request on their own virtqueue and the simulator\u0027s work function runs vdpasim_blk_handle_req() with no host-side action.\nS:C - The driver of the device (usually a guest VM) corrupts or reads host kernel memory outside blk-\u003ebuffer. That crosses from the guest\u0027s authority into the host kernel\u0027s, a guest-to-host boundary.\nC:H - VIRTIO_BLK_T_IN with an out-of-range sector makes vringh_iov_push_iotlb() copy from blk-\u003ebuffer + (sector \u003c\u003c 9). The attacker picks that offset from the kvzalloc buffer, and the host kernel memory is returned into the attacker\u0027s own descriptors.\nI:H - VIRTIO_BLK_T_OUT makes vringh_iov_pull_iotlb() copy attacker data to blk-\u003ebuffer + offset, and WRITE_ZEROES memsets there. The offset is under attacker control, which gives a write into host kernel memory that can lead to code execution.\nA:H - A write or read at a wild offset hits unmapped or critical host memory and oopses or panics the host kernel. That also takes down every other VM on the host."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T14:41:48.545Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/14acb0d44b7d90a077beb7b92b444b90bafda9d9"
        },
        {
          "url": "https://git.kernel.org/stable/c/a8a1413a2cfdbedc896249f461d6d92efbbfe21f"
        },
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          "url": "https://git.kernel.org/stable/c/d6dac17e20fd2abd0eb8c09d69fccf7426e12bcf"
        },
        {
          "url": "https://git.kernel.org/stable/c/0a8693f00c408d85f086ad85d29e7030bf1e2055"
        }
      ],
      "title": "vdpa_sim_blk: reject out-of-range sector starts",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97991",
    "datePublished": "2026-09-25T10:23:23.863Z",
    "dateReserved": "2026-09-25T10:18:58.209Z",
    "dateUpdated": "2026-09-25T14:41:48.545Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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                "product": "Linux",
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                  "drivers/vdpa/vdpa_sim/vdpa_sim_blk.c"
                ],
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                "vendor": "Linux",
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        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nvdpa_sim_blk: reject out-of-range sector starts\n\nvdpasim_blk_check_range() logs an invalid start sector but continues\nvalidating the request.  The subsequent unsigned capacity subtraction can\nunderflow and let an out-of-range buffer offset reach the data path.\n\nThe invalid offset is used by three request paths.  VIRTIO_BLK_T_OUT\ncopies guest data to blk-\u003ebuffer + offset through\nvringh_iov_pull_iotlb(), causing an out-of-bounds write in\n_copy_from_iter() or memcpy().  VIRTIO_BLK_T_IN copies from\nblk-\u003ebuffer + offset to the guest through vringh_iov_push_iotlb(),\ncausing an out-of-bounds read in _copy_to_iter().\nVIRTIO_BLK_T_WRITE_ZEROES passes blk-\u003ebuffer + offset to memset(),\ncausing an out-of-bounds write.\n\nReject starts at or beyond the capacity before the subtraction.  Treat the\ncapacity boundary as invalid because the IN and OUT paths round byte counts\ndown to sectors for validation but later copy the original byte counts.  A\nsub-sector request at the capacity boundary would otherwise still access\npast the end of the buffer.\n\nI found this bug myself, though the patch was written with AI assistance."
          }
        ],
        "id": "CVE-2026-97991",
        "lastModified": "2026-09-25T15:18:03.453",
        "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": "2026-09-25T11:17:27.220",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/0a8693f00c408d85f086ad85d29e7030bf1e2055"
          },
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/d6dac17e20fd2abd0eb8c09d69fccf7426e12bcf"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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