{"api_version":"1","generated_at":"2026-09-25T08:35:15+00:00","cve":"CVE-2026-93079","urls":{"html":"https://cve.report/CVE-2026-93079","api":"https://cve.report/api/cve/CVE-2026-93079.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-93079","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-93079"},"summary":{"title":"cxl/features: Reject Get Feature count larger than the output buffer","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-17 17:18:01","updated_at":"2026-09-18 18:18:20"},"problem_types":[],"metrics":[{"version":"3.1","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"DECLARED","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","data":{"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"}}],"references":[{"url":"https://git.kernel.org/stable/c/3f02031a0a53de0d3ef066c92d0486b2b11be40c","name":"https://git.kernel.org/stable/c/3f02031a0a53de0d3ef066c92d0486b2b11be40c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/329ea475581c647a680a6937e353c1a6e2534b40","name":"https://git.kernel.org/stable/c/329ea475581c647a680a6937e353c1a6e2534b40","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/4bf6bac375076ced2fa4b3fef8739bd985f93456","name":"https://git.kernel.org/stable/c/4bf6bac375076ced2fa4b3fef8739bd985f93456","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-93079","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93079","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5908f3ed6dc209e5c824e63afda7545805f75a7e 3f02031a0a53de0d3ef066c92d0486b2b11be40c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5908f3ed6dc209e5c824e63afda7545805f75a7e 329ea475581c647a680a6937e353c1a6e2534b40 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5908f3ed6dc209e5c824e63afda7545805f75a7e 4bf6bac375076ced2fa4b3fef8739bd985f93456 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.15","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.15 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.52 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.6 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"93079","cve":"CVE-2026-93079","epss":"0.001610000","percentile":"0.057600000","score_date":"2026-09-21","updated_at":"2026-09-22 00:03:18"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/cxl/core/features.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"3f02031a0a53de0d3ef066c92d0486b2b11be40c","status":"affected","version":"5908f3ed6dc209e5c824e63afda7545805f75a7e","versionType":"git"},{"lessThan":"329ea475581c647a680a6937e353c1a6e2534b40","status":"affected","version":"5908f3ed6dc209e5c824e63afda7545805f75a7e","versionType":"git"},{"lessThan":"4bf6bac375076ced2fa4b3fef8739bd985f93456","status":"affected","version":"5908f3ed6dc209e5c824e63afda7545805f75a7e","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/cxl/core/features.c"],"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"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.52","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.6","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.52","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.6","versionStartIncluding":"6.15","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc1","versionStartIncluding":"6.15","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","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."}],"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 - 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."}]}],"providerMetadata":{"dateUpdated":"2026-09-18T17:55:53.599Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/3f02031a0a53de0d3ef066c92d0486b2b11be40c"},{"url":"https://git.kernel.org/stable/c/329ea475581c647a680a6937e353c1a6e2534b40"},{"url":"https://git.kernel.org/stable/c/4bf6bac375076ced2fa4b3fef8739bd985f93456"}],"title":"cxl/features: Reject Get Feature count larger than the output buffer","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-93079","datePublished":"2026-09-17T16:11:00.350Z","dateReserved":"2026-09-17T15:57:05.661Z","dateUpdated":"2026-09-18T17:55:53.599Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-17 17:18:01","lastModifiedDate":"2026-09-18 18:18:20","problem_types":[],"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:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"93079","Ordinal":"1","Title":"cxl/features: Reject Get Feature count larger than the output bu","CVE":"CVE-2026-93079","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"93079","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"cxl/features: Reject Get Feature count larger than the output bu"}]}}}