CVE-2026-93079

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-93079", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-17T15:57:05.661Z", "datePublished": "2026-09-17T16:11:00.350Z", "dateUpdated": "2026-10-19T09:05:15.062Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:05:15.062Z"}, "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": {"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"}, "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."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/cxl/core/features.c"], "versions": [{"version": "5908f3ed6dc209e5c824e63afda7545805f75a7e", "lessThan": "3f02031a0a53de0d3ef066c92d0486b2b11be40c", "status": "affected", "versionType": "git"}, {"version": "5908f3ed6dc209e5c824e63afda7545805f75a7e", "lessThan": "329ea475581c647a680a6937e353c1a6e2534b40", "status": "affected", "versionType": "git"}, {"version": "5908f3ed6dc209e5c824e63afda7545805f75a7e", "lessThan": "4bf6bac375076ced2fa4b3fef8739bd985f93456", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/cxl/core/features.c"], "versions": [{"version": "6.15", "status": "affected"}, {"version": "0", "lessThan": "6.15", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.52", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "6.18.52"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.2.6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.15", "versionEndExcluding": "7.3"}]}]}], "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"}}}}

{}

{"affected": [{"affectedData": [{"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", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "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."}], "id": "CVE-2026-93079", "lastModified": "2026-10-19T10:16:57.850", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 5.9, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-09-17T17:18:01.850", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/329ea475581c647a680a6937e353c1a6e2534b40"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/3f02031a0a53de0d3ef066c92d0486b2b11be40c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/4bf6bac375076ced2fa4b3fef8739bd985f93456"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[5908f3ed6dc209e5c824e63afda7545805f75a7e,3f02031a0a53de0d3ef066c92d0486b2b11be40c)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[5908f3ed6dc209e5c824e63afda7545805f75a7e,329ea475581c647a680a6937e353c1a6e2534b40)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[5908f3ed6dc209e5c824e63afda7545805f75a7e,4bf6bac375076ced2fa4b3fef8739bd985f93456)"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "6.15"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[0,6.15)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[6.18.52,6.19.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.2.6,7.3.0)"}}, {"platform": null, "status": "unaffected", "versions": {"scheme": "generic", "value": "[7.3-rc1,*]"}}], "enrichment": {"confidence": 99.0, "confidence_source": "inferred", "scores": [{"score": 99.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-09-19T09:45:03.925822+00:00", "updated": "2026-09-19T22:45:06.156946+00:00", "vendors": ["linux", "linux$PRODUCT$linux_kernel"], "weaknesses": ["CWE-122"]}