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vuln-cve/data/2026/89xxx/CVE-2026-89632.json
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{
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"cveMetadata": {
"cveId": "CVE-2026-89632",
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"state": "PUBLISHED",
"assignerShortName": "Linux",
"dateReserved": "2026-09-11T19:38:34.738Z",
"datePublished": "2026-09-11T19:45:27.325Z",
"dateUpdated": "2026-10-21T12:48:04.460Z"
},
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"cna": {
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"shortName": "Linux",
"dateUpdated": "2026-10-21T12:48:04.460Z"
},
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()\n\nreparse_buf_ptr() reads buf->ReparseDataLength before checking that\ncount covers the full fixed header:\n\n buf = (struct reparse_data_buffer *)((u8 *)io + off);\n len = sizeof(*buf); /* 8 bytes */\n rdlen = le16_to_cpu(buf->ReparseDataLength); /* offset 4, 2 bytes */\n\n if (count < len || count < rdlen + len) /* check comes after */\n\nstruct reparse_data_buffer has ReparseDataLength at offset 4. If a\nserver returns OutputCount < 6, the read at offset 4-5 reaches past\nthe end of the received data. The off+count bounds against iov_len\nwere already validated, but that does not protect against count being\nsmaller than sizeof(*buf).\n\nSplit the check: verify count >= sizeof(*buf) before reading\nReparseDataLength, then verify count covers the data region."
}
],
"metrics": [
{
"cvssV3_1": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"baseScore": 8.2,
"baseSeverity": "HIGH"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The flaw is in the in-kernel SMB client parser for FSCTL_GET_REPARSE_POINT IOCTL replies on TCP/445. A malicious, compromised, or on-path SMB server reaches reparse_buf_ptr() with crafted OutputOffset/OutputCount; this matches sibling client response-parsing scores such as CVE-2026-46155 and CVE-2024-49996.\nAC:L - The server fully controls OutputOffset and OutputCount. A successful IOCTL PDU with OutputCount < 6 and OutputOffset near iov_len (for example a 448-byte cifs_small_rq-sized frame) deterministically loads ReparseDataLength past the received payload, with no race or attacker-uncontrollable layout.\nPR:N - The attacker is the remote SMB server (or a MITM on an unsigned session) and needs no account, credentials, or capabilities on the victim client. GET_REPARSE runs on an already established tree connect after ordinary CREATE/lookup; the client authenticates to the server, not the reverse.\nUI:N - On an already-mounted or automounted CIFS share, any routine lookup/stat of a reparse point — including files the server flags as reparse in CREATE — issues FSCTL_GET_REPARSE_POINT. Backup jobs, indexers, and inode revalidation hit the parser with no contemporaneous victim mount action.\nS:U - The two-byte out-of-bounds load and any resulting oops stay inside the client kernel's security authority. The bug does not cross a VM, IOMMU, or sandbox boundary.\nC:L - The use-before-check reads exactly two bytes of ReparseDataLength past the IOCTL output region (and, when the PDU fills cifs_small_rq, past that 448-byte slab). Those bytes are passed only to smb_EIO2 tracing, so disclosure is strictly bounded, matching CVE-2026-64448 rather than unbounded heap leaks.\nI:N - The out-of-bounds access is a u16 load used only in the subsequent length check and error trace. On failure the helper returns -EIO and does not install a reparse tag or copy payload, so there is no kernel write or metadata-corruption primitive.\nA:H - A PDU that fills the cifs_small_rq or cifs_request slab with OutputOffset at the object end makes the two-byte load a true slab-out-of-bounds access, which KASAN reports as a BUG and which can oops/panic if the next page is unmapped. A malicious server can retrigger it on every GET_REPARSE."
}
]
}
],
"affected": [
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/smb/client/smb2inode.c"
],
"versions": [
{
"version": "a158bb66b1373866d9fd5997565a58a573085539",
"lessThan": "b70bc592afd19732e2e4563300ebe8f974280365",
"status": "affected",
"versionType": "git"
},
{
"version": "67ec9949b0dfe78c99e110dd975eb7dc5645630c",
"lessThan": "711cf71300d7992f450600df8864917d3538679f",
"status": "affected",
"versionType": "git"
},
{
"version": "67ec9949b0dfe78c99e110dd975eb7dc5645630c",
"lessThan": "05f78e6cf34ea3a285053bd5999e08e8ac298bd5",
"status": "affected",
"versionType": "git"
},
{
"version": "6.6.32",
"lessThan": "6.6.160",
"status": "affected",
"versionType": "semver"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/smb/client/smb2inode.c"
],
"versions": [
{
"version": "6.8",
"status": "affected"
},
{
"version": "0",
"lessThan": "6.8",
"status": "unaffected",
"versionType": "semver"
},
{
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"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "semver"
},
{
"version": "7.2.4",
"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": "6.6.32",
"versionEndExcluding": "6.6.160"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.8",
"versionEndExcluding": "7.2.4"
},
{
"vulnerable": true,
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.8",
"versionEndExcluding": "7.3"
}
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],
"references": [
{
"url": "https://git.kernel.org/stable/c/b70bc592afd19732e2e4563300ebe8f974280365"
},
{
"url": "https://git.kernel.org/stable/c/711cf71300d7992f450600df8864917d3538679f"
},
{
"url": "https://git.kernel.org/stable/c/05f78e6cf34ea3a285053bd5999e08e8ac298bd5"
}
],
"title": "smb: client: fix use-before-check of ReparseDataLength in reparse_buf_ptr()",
"x_generator": {
"engine": "bippy-1.2.0"
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},
"adp": [
{
"metrics": [
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"other": {
"type": "ssvc",
"content": {
"id": "CVE-2026-89632",
"role": "CISA Coordinator",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "partial"
}
],
"version": "2.0.3",
"timestamp": "2026-10-16T19:24:44.423758Z"
}
}
}
],
"title": "CISA ADP Vulnrichment",
"providerMetadata": {
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP",
"dateUpdated": "2026-10-16T19:26:45.525Z"
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}