159 lines
9.3 KiB
JSON
159 lines
9.3 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-2026-93079",
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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": "2026-09-17T15:57:05.661Z",
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"datePublished": "2026-09-17T16:11:00.350Z",
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"dateUpdated": "2026-10-19T09:05:15.062Z"
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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": "2026-10-19T09:05:15.062Z"
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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\ncxl/features: Reject Get Feature count larger than the output buffer\n\ncxlctl_get_feature() sizes its output buffer from the user's\nfwctl_rpc.out_len, but the device is told to write\ncxl_mbox_get_feat_in.count bytes into rpc_out->payload, which is a\nseparate user-controlled value. Nothing bounds count against out_len, so\na small out_len with a large count overflows the kvzalloc()'d buffer.\nA heap OOB write reachable from FWCTL_RPC.\n\nReject requests where count exceeds the available payload room, before\nallocating."
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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:U/C:H/I:H/A:H",
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"baseScore": 7.8,
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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 - The overflow is triggered by ioctl(FWCTL_RPC) on /dev/fwctl/fwctlN via fwctl_fops_ioctl()->fwctl_cmd_rpc()->cxlctl_fw_rpc()->cxlctl_get_feature(). The mismatched inputs are local userspace fields fwctl_rpc.out_len and cxl_mbox_get_feat_in.count on a CXL_MBOX_OP_GET_FEATURE (0x0501) RPC, not bytes from a network or CXL-peer protocol message.\nAC:L - The caller sets both fwctl_rpc.out_len and get_feat_in.count in one GET_FEATURE RPC. cxlctl_get_feature() kvzallocs out_len then passes count to cxl_get_feature() as the mailbox output length, so a short out_len with count larger than the payload room overflows on memcpy_fromio() in __cxl_pci_mbox_send_cmd(). Feature size is learned first via GET_SUPPORTED_FEATURES; no race is required.\nPR:L - CXL_MBOX_OP_GET_FEATURE is accepted at FWCTL_RPC_CONFIGURATION; fwctl_cmd_rpc() checks CAP_SYS_RAWIO only for FWCTL_RPC_DEBUG_WRITE_FULL, and cxlctl_open_uctx() is a no-op. Opening /dev/fwctl/fwctlN is sufficient, and that node is routinely granted to management/VMM users without init-namespace root.\nUI:N - The attacker opens /dev/fwctl/fwctlN and issues ioctl(FWCTL_RPC) with opcode CXL_MBOX_OP_GET_FEATURE themselves; no victim action such as mounting a volume or opening a file is required.\nS:U - __cxl_pci_mbox_send_cmd() memcpy_fromio()s the Get Feature mailbox payload into the host kernel heap object rpc_out->payload allocated by cxlctl_get_feature(). The corruption stays in the host kernel CXL/fwctl path and is not a guest-to-host, IOMMU, or other changed-scope boundary.\nC:H - cxl_get_feature() tells the device to write get_feat_in.count bytes (u16, up to 65535) into rpc_out->payload, overflowing the kvzalloc(out_len) object via memcpy_fromio(). That heap out-of-bounds write is memory corruption that can be turned into an arbitrary-read primitive.\nI:H - The same GET_FEATURE path is a kernel heap out-of-bounds write: __cxl_pci_mbox_send_cmd() copies the mailbox payload into feat_out past the end of the out_len-sized allocation. The attacker chooses count and can SET_FEATURE first on a changeable user feature, so adjacent heap objects can be overwritten.\nA:H - Overflowing the kvzalloc buffer in cxlctl_get_feature() corrupts adjacent heap metadata and oopses, and out_len==0 makes kvzalloc return ZERO_SIZE_PTR so the mailbox write through rpc_out->payload faults immediately. Either outcome is a repeatable kernel panic."
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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/cxl/core/features.c"
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],
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"versions": [
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{
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"version": "5908f3ed6dc209e5c824e63afda7545805f75a7e",
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"lessThan": "3f02031a0a53de0d3ef066c92d0486b2b11be40c",
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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": "5908f3ed6dc209e5c824e63afda7545805f75a7e",
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"lessThan": "329ea475581c647a680a6937e353c1a6e2534b40",
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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": "5908f3ed6dc209e5c824e63afda7545805f75a7e",
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"lessThan": "4bf6bac375076ced2fa4b3fef8739bd985f93456",
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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/cxl/core/features.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": "6.18.52",
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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": "7.2.6",
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"lessThanOrEqual": "7.2.*",
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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": "7.3",
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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": "6.18.52"
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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": "7.2.6"
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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": "7.3"
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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/3f02031a0a53de0d3ef066c92d0486b2b11be40c"
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},
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{
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"url": "https://git.kernel.org/stable/c/329ea475581c647a680a6937e353c1a6e2534b40"
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},
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{
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"url": "https://git.kernel.org/stable/c/4bf6bac375076ced2fa4b3fef8739bd985f93456"
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}
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],
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"title": "cxl/features: Reject Get Feature count larger than the output buffer",
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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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} |