159 lines
11 KiB
JSON
159 lines
11 KiB
JSON
{
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"dataType": "CVE_RECORD",
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"dataVersion": "5.2",
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"cveMetadata": {
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"cveId": "CVE-2026-74702",
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"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"state": "PUBLISHED",
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"assignerShortName": "Linux",
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"dateReserved": "2026-08-15T05:44:03.927Z",
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"datePublished": "2026-08-22T15:33:02.223Z",
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"dateUpdated": "2026-08-25T05:41:45.057Z"
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},
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"containers": {
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"cna": {
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"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"shortName": "Linux",
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"dateUpdated": "2026-08-25T05:41:45.057Z"
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},
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"descriptions": [
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{
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"lang": "en",
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"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's 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 > SG_CHUNK_SIZE); /* 129 > 128 */\n\nThe kernel reported the following call trace and register state:\n\n Call Trace:\n <TASK>\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 </TASK>\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."
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}
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],
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"metrics": [
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{
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"cvssV3_1": {
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"version": "3.1",
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"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
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"baseScore": 8.8,
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"baseSeverity": "HIGH"
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},
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"scenarios": [
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{
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"lang": "en",
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"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 > 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 > 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."
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}
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]
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}
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],
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"affected": [
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "unaffected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"drivers/vhost/scsi.c"
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],
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"versions": [
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{
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"version": "bf2d650391be508dd8b5e188b65ed32300cf3489",
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"lessThan": "a06e4611d45518896fbff4f45d9581578b107e91",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "bf2d650391be508dd8b5e188b65ed32300cf3489",
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"lessThan": "9a3eb77a612f9d158e4d27df43677a014e9cfa55",
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"status": "affected",
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"versionType": "git"
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},
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{
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"version": "bf2d650391be508dd8b5e188b65ed32300cf3489",
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"lessThan": "42bc45df5905e2b7dccb72adaf7730f66cfbe03f",
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"status": "affected",
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"versionType": "git"
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}
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]
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},
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{
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"product": "Linux",
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"vendor": "Linux",
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"defaultStatus": "affected",
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"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"programFiles": [
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"drivers/vhost/scsi.c"
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],
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"versions": [
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{
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"version": "6.15",
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"status": "affected"
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},
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{
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"version": "0",
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"lessThan": "6.15",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "6.18.45",
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"lessThanOrEqual": "6.18.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.1.9",
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"lessThanOrEqual": "7.1.*",
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"status": "unaffected",
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"versionType": "semver"
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},
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{
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"version": "7.2",
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"lessThanOrEqual": "*",
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"status": "unaffected",
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"versionType": "original_commit_for_fix"
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}
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]
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}
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],
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"cpeApplicability": [
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{
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"nodes": [
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{
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"operator": "OR",
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"negate": false,
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"cpeMatch": [
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "6.18.45"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "7.1.9"
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},
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{
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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "6.15",
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"versionEndExcluding": "7.2"
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}
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]
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}
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]
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}
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],
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"references": [
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{
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"url": "https://git.kernel.org/stable/c/a06e4611d45518896fbff4f45d9581578b107e91"
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},
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{
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"url": "https://git.kernel.org/stable/c/9a3eb77a612f9d158e4d27df43677a014e9cfa55"
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},
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{
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"url": "https://git.kernel.org/stable/c/42bc45df5905e2b7dccb72adaf7730f66cfbe03f"
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}
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],
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"title": "vhost-scsi: reject feature changes after endpoint",
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"x_generator": {
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"engine": "bippy-1.2.0"
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}
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}
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}
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} |