CVE-2026-74702 (GCVE-0-2026-74702)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:33 – Updated: 2026-08-25 05:41
VLAI
Title
vhost-scsi: reject feature changes after endpoint
Summary
In the Linux kernel, the following vulnerability has been resolved: vhost-scsi: reject feature changes after endpoint vhost_scsi_setup_vq_cmds() runs from VHOST_SCSI_SET_ENDPOINT and allocates each command's protection scatterlist array (prot_sgl) according to the acknowledged VIRTIO_SCSI_F_T10_PI bit. The command pools are not rebuilt when VHOST_SET_FEATURES changes that bit later. Although virtio feature bits must not change after feature negotiation, vhost_scsi_set_features() currently accepts such a request after the endpoint is active and updates acked_features. Enabling T10-PI after endpoint setup therefore leaves prot_sgl NULL while the I/O path follows the new feature bit. For a 129-page protection payload, vhost_scsi_mapal() passes the missing first chunk to sg_alloc_table_chained(): sg_alloc_table_chained(table, 129, first_chunk=NULL, nents_first_chunk=inline_sg_cnt) sg_pool_index() then hits: BUG_ON(nents > SG_CHUNK_SIZE); /* 129 > 128 */ The kernel reported the following call trace and register state: Call Trace: <TASK> ? __sg_alloc_table+0x1d8/0x250 ? __pfx_vhost_run_work_list+0x10/0x10 [vhost] sg_alloc_table_chained+0x59/0xf0 ? __pfx_sg_pool_alloc+0x10/0x10 ? vhost_scsi_calc_sgls.constprop.0+0x43/0x60 [vhost_scsi] vhost_scsi_handle_vq+0xf02/0x1700 [vhost_scsi] ? __pfx_vhost_scsi_handle_vq+0x10/0x10 [vhost_scsi] vhost_scsi_handle_kick+0x37/0x50 [vhost_scsi] vhost_run_work_list+0x8e/0xd0 [vhost] vhost_task_fn+0xe1/0x210 ret_from_fork+0x348/0x540 </TASK> RIP: 0010:0x4 CR2 = 0x4 RSP: 0018:ffffc90000dbf940 EFLAGS: 00010202 RAX: ffffffff82396810 RBX: ffff88811dc28b80 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000081 VHOST_F_LOG_ALL is a vhost-specific runtime feature and remains the only exception. Reject changes to any feature other than VHOST_F_LOG_ALL while the endpoint is active. This preserves the existing runtime log toggle while preventing feature-dependent command resources and data-path state from becoming inconsistent. Userspace must clear the endpoint before changing any other negotiated feature and set the endpoint up again afterward.
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: bf2d650391be508dd8b5e188b65ed32300cf3489 , < a06e4611d45518896fbff4f45d9581578b107e91 (git)
Affected: bf2d650391be508dd8b5e188b65ed32300cf3489 , < 9a3eb77a612f9d158e4d27df43677a014e9cfa55 (git)
Affected: bf2d650391be508dd8b5e188b65ed32300cf3489 , < 42bc45df5905e2b7dccb72adaf7730f66cfbe03f (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": [
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              "status": "affected",
              "version": "bf2d650391be508dd8b5e188b65ed32300cf3489",
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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"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.45",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.9",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.45",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.9",
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                  "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: reject feature changes after endpoint\n\nvhost_scsi_setup_vq_cmds() runs from VHOST_SCSI_SET_ENDPOINT and allocates\neach command\u0027s protection scatterlist array (prot_sgl) according to the\nacknowledged VIRTIO_SCSI_F_T10_PI bit.  The command pools are not rebuilt\nwhen VHOST_SET_FEATURES changes that bit later.\n\nAlthough virtio feature bits must not change after feature negotiation,\nvhost_scsi_set_features() currently accepts such a request after the\nendpoint is active and updates acked_features.  Enabling T10-PI after\nendpoint setup therefore leaves prot_sgl NULL while the I/O path follows\nthe new feature bit.\n\nFor a 129-page protection payload, vhost_scsi_mapal() passes the missing\nfirst chunk to sg_alloc_table_chained():\n\n  sg_alloc_table_chained(table, 129, first_chunk=NULL,\n                         nents_first_chunk=inline_sg_cnt)\n\nsg_pool_index() then hits:\n\n  BUG_ON(nents \u003e SG_CHUNK_SIZE);   /* 129 \u003e 128 */\n\nThe kernel reported the following call trace and register state:\n\n  Call Trace:\n   \u003cTASK\u003e\n   ? __sg_alloc_table+0x1d8/0x250\n   ? __pfx_vhost_run_work_list+0x10/0x10 [vhost]\n   sg_alloc_table_chained+0x59/0xf0\n   ? __pfx_sg_pool_alloc+0x10/0x10\n   ? vhost_scsi_calc_sgls.constprop.0+0x43/0x60 [vhost_scsi]\n   vhost_scsi_handle_vq+0xf02/0x1700 [vhost_scsi]\n   ? __pfx_vhost_scsi_handle_vq+0x10/0x10 [vhost_scsi]\n   vhost_scsi_handle_kick+0x37/0x50 [vhost_scsi]\n   vhost_run_work_list+0x8e/0xd0 [vhost]\n   vhost_task_fn+0xe1/0x210\n   ret_from_fork+0x348/0x540\n   \u003c/TASK\u003e\n\n  RIP: 0010:0x4\n  CR2 = 0x4\n  RSP: 0018:ffffc90000dbf940 EFLAGS: 00010202\n  RAX: ffffffff82396810 RBX: ffff88811dc28b80 RCX: 0000000000000000\n  RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000081\n\nVHOST_F_LOG_ALL is a vhost-specific runtime feature and remains the only\nexception.\n\nReject changes to any feature other than VHOST_F_LOG_ALL while the\nendpoint is active.  This preserves the existing runtime log toggle while\npreventing feature-dependent command resources and data-path state from\nbecoming inconsistent.  Userspace must clear the endpoint before changing\nany other negotiated feature and set the endpoint up again afterward."
        }
      ],
      "metrics": [
        {
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            "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 - vhost-scsi is only reachable through virtio-scsi virtqueue kicks and VHOST_* ioctls on /dev/vhost-scsi by the VMM or a VM guest; it is not exposed via any network protocol or remote packet path.\nAC:L - Once VIRTIO_SCSI_F_T10_PI is toggled after VHOST_SCSI_SET_ENDPOINT, a virtio-scsi request with protection data spanning 129+ pages deterministically drives vhost_scsi_mapal() into sg_alloc_table_chained() with NULL prot_sgl and triggers BUG_ON(nents \u003e SG_CHUNK_SIZE); no races or victim-specific memory layout are required.\nPR:L - No host root or CAP_SYS_ADMIN is needed: an unprivileged cloud VM tenant can negotiate virtio-scsi T10-PI (QEMU propagates VHOST_SET_FEATURES) and submit the oversized PI I/O, and vhost ioctls have no capability gate for any process holding the vhost-scsi fd.\nUI:N - Exploitation requires only attacker-controlled virtio-scsi I/O and/or VMM feature updates during normal VM operation; no administrator or end-user action beyond routine VM use is needed.\nS:C - On KVM hosts using virtio-scsi with the vhost backend, a malicious guest reaches host-kernel vhost-scsi worker code and can panic the hypervisor, crossing the guest-to-host virtual machine security boundary.\nC:H - Enabling T10-PI after endpoint setup leaves prot_sgl NULL while the data path allocates and maps protection scatterlists from the shared sg pool; the reporter hit a fault at address 0x4, and smaller requests can complete with mismatched inline/pool metadata that corrupts kernel heap bookkeeping on free.\nI:H - Attacker-controlled protection iterators are mapped into kernel scatterlists passed to the LIO/TCM target stack under inconsistent feature state, yielding heap writes and unreliable sg_free_table_chained() teardown that can be leveraged for control-flow hijack beyond the immediate BUG_ON.\nA:H - The demonstrated path hits BUG_ON(nents \u003e SG_CHUNK_SIZE) in sg_pool_index() from the vhost worker during vhost_scsi_handle_vq(), producing a host kernel oops/panic that terminates the hypervisor and all co-resident VMs."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-25T05:41:45.057Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/a06e4611d45518896fbff4f45d9581578b107e91"
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        {
          "url": "https://git.kernel.org/stable/c/9a3eb77a612f9d158e4d27df43677a014e9cfa55"
        },
        {
          "url": "https://git.kernel.org/stable/c/42bc45df5905e2b7dccb72adaf7730f66cfbe03f"
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      ],
      "title": "vhost-scsi: reject feature changes after endpoint",
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        "engine": "bippy-1.2.0"
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74702",
    "datePublished": "2026-08-22T15:33:02.223Z",
    "dateReserved": "2026-08-15T05:44:03.927Z",
    "dateUpdated": "2026-08-25T05:41:45.057Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74702",
      "date": "2026-09-01",
      "epss": "0.00127",
      "percentile": "0.02656"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74702\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-22T16:16:44.873\",\"lastModified\":\"2026-08-25T06:18:54.117\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nvhost-scsi: reject feature changes after endpoint\\n\\nvhost_scsi_setup_vq_cmds() runs from VHOST_SCSI_SET_ENDPOINT and allocates\\neach command\u0027s protection scatterlist array (prot_sgl) according to the\\nacknowledged VIRTIO_SCSI_F_T10_PI bit.  The command pools are not rebuilt\\nwhen VHOST_SET_FEATURES changes that bit later.\\n\\nAlthough virtio feature bits must not change after feature negotiation,\\nvhost_scsi_set_features() currently accepts such a request after the\\nendpoint is active and updates acked_features.  Enabling T10-PI after\\nendpoint setup therefore leaves prot_sgl NULL while the I/O path follows\\nthe new feature bit.\\n\\nFor a 129-page protection payload, vhost_scsi_mapal() passes the missing\\nfirst chunk to sg_alloc_table_chained():\\n\\n  sg_alloc_table_chained(table, 129, first_chunk=NULL,\\n                         nents_first_chunk=inline_sg_cnt)\\n\\nsg_pool_index() then hits:\\n\\n  BUG_ON(nents \u003e SG_CHUNK_SIZE);   /* 129 \u003e 128 */\\n\\nThe kernel reported the following call trace and register state:\\n\\n  Call Trace:\\n   \u003cTASK\u003e\\n   ? __sg_alloc_table+0x1d8/0x250\\n   ? __pfx_vhost_run_work_list+0x10/0x10 [vhost]\\n   sg_alloc_table_chained+0x59/0xf0\\n   ? __pfx_sg_pool_alloc+0x10/0x10\\n   ? vhost_scsi_calc_sgls.constprop.0+0x43/0x60 [vhost_scsi]\\n   vhost_scsi_handle_vq+0xf02/0x1700 [vhost_scsi]\\n   ? __pfx_vhost_scsi_handle_vq+0x10/0x10 [vhost_scsi]\\n   vhost_scsi_handle_kick+0x37/0x50 [vhost_scsi]\\n   vhost_run_work_list+0x8e/0xd0 [vhost]\\n   vhost_task_fn+0xe1/0x210\\n   ret_from_fork+0x348/0x540\\n   \u003c/TASK\u003e\\n\\n  RIP: 0010:0x4\\n  CR2 = 0x4\\n  RSP: 0018:ffffc90000dbf940 EFLAGS: 00010202\\n  RAX: ffffffff82396810 RBX: ffff88811dc28b80 RCX: 0000000000000000\\n  RDX: 0000000000000000 RSI: 0000000000000820 RDI: 0000000000000081\\n\\nVHOST_F_LOG_ALL is a vhost-specific runtime feature and remains the only\\nexception.\\n\\nReject changes to any feature other than VHOST_F_LOG_ALL while the\\nendpoint is active.  This preserves the existing runtime log toggle while\\npreventing feature-dependent command resources and data-path state from\\nbecoming inconsistent.  Userspace must clear the endpoint before changing\\nany other negotiated feature and set the endpoint up again afterward.\"}],\"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\":\"bf2d650391be508dd8b5e188b65ed32300cf3489\",\"lessThan\":\"a06e4611d45518896fbff4f45d9581578b107e91\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"bf2d650391be508dd8b5e188b65ed32300cf3489\",\"lessThan\":\"9a3eb77a612f9d158e4d27df43677a014e9cfa55\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"bf2d650391be508dd8b5e188b65ed32300cf3489\",\"lessThan\":\"42bc45df5905e2b7dccb72adaf7730f66cfbe03f\",\"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: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/42bc45df5905e2b7dccb72adaf7730f66cfbe03f\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9a3eb77a612f9d158e4d27df43677a014e9cfa55\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a06e4611d45518896fbff4f45d9581578b107e91\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-25T08:54:51+00:00",
      "cve": "CVE-2026-74702",
      "id": "CVE-2026-74702",
      "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: reject feature changes after endpoint",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74702.json",
      "version": "3"
    }
  }
}



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