201 lines
11 KiB
JSON
201 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-2025-39942",
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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": "2025-04-16T07:20:57.148Z",
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"datePublished": "2025-10-04T07:31:04.810Z",
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"dateUpdated": "2026-08-05T12:06:17.026Z"
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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": "2026-08-05T12:06:17.026Z"
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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\nksmbd: smbdirect: verify remaining_data_length respects max_fragmented_recv_size\n\nThis is inspired by the check for data_offset + data_length."
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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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
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"baseScore": 7.5,
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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:N - The flaw is in ksmbd's in-kernel SMB Direct (RDMA) transport receive completion handler, which parses `smb_direct_data_transfer` headers straight off the wire from a remote SMB client on the SMB Direct port (5445/445 over iWARP or RoCEv2, both routable). No local access is needed — a single crafted RDMA send from a remote peer reaches the vulnerable code.\nAC:L - `remaining_data_length` is a plain header field the attacker writes directly, and the attacker also controls `preferred_send_size` in the SMB Direct negotiate request that determines `max_fragmented_recv_size`, so the unsatisfiable-reassembly condition is set up deterministically with two packets. No race, no memory-layout grooming, no timing dependency.\nPR:N - `recv_done()` is transport-level code that runs on every data transfer message before any SMB2 session setup or credential verification, and ksmbd never validates the negotiate request's `preferred_send_size`, letting an unauthenticated peer shrink the reassembly capacity below the pre-auth `SMB3_MAX_MSGSIZE` PDU limit and wedge the connection thread with no credentials at all.\nUI:N - The server processes the malformed data transfer message automatically as part of normal SMB Direct receive completion handling. No administrator or user action on the target is involved.\nS:U - The impact is confined to the ksmbd server's own kernel context — the stalled connection thread and pinned kernel allocations — with no crossing into a different security authority such as a hypervisor or IOMMU boundary.\nC:N - With the parent commit's `data_offset`/`data_length` validation in place, every `memcpy()` source in `smb_direct_read()` stays within the DMA'd `wc->byte_len` region, so no out-of-bounds or stale buffer contents are read and nothing is disclosed to the attacker beyond data they supplied themselves.\nI:N - The unsigned overflow of `data_length + remaining_data_length` only desynchronizes RFC1002 PDU framing on a byte stream the attacker already fully controls, and `get_rfc1002_len()`'s `0xFFFFFF` mask plus the `max_allowed_pdu_size` check prevent any under-allocation or out-of-bounds write, so no kernel data or control flow is modified.\nA:H - A remote peer can request reassembly of a message larger than the transport can ever hold (bounded by 255 recvmsg buffers), permanently blocking the ksmbd connection kthread in `wait_event_interruptible()` while it pins a multi-megabyte `kvmalloc` buffer and the entire receive buffer pool; repeating this across connections exhausts kernel memory and server threads, denying SMB service."
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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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"fs/smb/server/transport_rdma.c"
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],
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"versions": [
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{
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"version": "2ea086e35c3d726a3bacd0a971c1f02a50e98206",
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"lessThan": "196a3a7676d726ee67621ea2bf3b7815ac2685b4",
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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": "2ea086e35c3d726a3bacd0a971c1f02a50e98206",
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"lessThan": "d3cb3f209d35c44b7ee74f77ed27ebb28995b9ce",
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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": "2ea086e35c3d726a3bacd0a971c1f02a50e98206",
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"lessThan": "9644798294c7287e65a7b26e35aa6d2ce3345bcc",
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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": "2ea086e35c3d726a3bacd0a971c1f02a50e98206",
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"lessThan": "c64b915bb3d9339adcae5db4be2c35ffbef5e615",
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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": "2ea086e35c3d726a3bacd0a971c1f02a50e98206",
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"lessThan": "e1868ba37fd27c6a68e31565402b154beaa65df0",
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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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"fs/smb/server/transport_rdma.c"
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],
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"versions": [
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{
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"version": "5.15",
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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": "5.15",
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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": "6.1.154",
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"lessThanOrEqual": "6.1.*",
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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": "6.6.108",
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"lessThanOrEqual": "6.6.*",
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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": "6.12.49",
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"lessThanOrEqual": "6.12.*",
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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": "6.16.9",
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"lessThanOrEqual": "6.16.*",
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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": "6.17",
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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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"vulnerable": true,
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "5.15",
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"versionEndExcluding": "6.1.154"
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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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{
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"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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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/196a3a7676d726ee67621ea2bf3b7815ac2685b4"
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},
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{
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"url": "https://git.kernel.org/stable/c/d3cb3f209d35c44b7ee74f77ed27ebb28995b9ce"
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},
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{
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"url": "https://git.kernel.org/stable/c/9644798294c7287e65a7b26e35aa6d2ce3345bcc"
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},
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{
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"url": "https://git.kernel.org/stable/c/c64b915bb3d9339adcae5db4be2c35ffbef5e615"
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},
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{
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"url": "https://git.kernel.org/stable/c/e1868ba37fd27c6a68e31565402b154beaa65df0"
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}
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],
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"title": "ksmbd: smbdirect: verify remaining_data_length respects max_fragmented_recv_size",
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"x_generator": {
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} |