{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40084", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.161Z", "datePublished": "2025-10-29T13:37:03.185Z", "dateUpdated": "2026-08-05T12:07:38.947Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:07:38.947Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: transport_ipc: validate payload size before reading handle\n\nhandle_response() dereferences the payload as a 4-byte handle without\nverifying that the declared payload size is at least 4 bytes. A malformed\nor truncated message from ksmbd.mountd can lead to a 4-byte read past the\ndeclared payload size. Validate the size before dereferencing.\n\nThis is a minimal fix to guard the initial handle read." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "baseScore": 7.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is reached only via a generic netlink message to the `SMBD_GENL` family (`handle_generic_event` → `handle_response`), which requires a local socket on the machine; a remote SMB client on TCP/445 cannot inject IPC responses.\nAC:L - The attacker fully controls the crafted netlink message — a zero-length `KSMBD_EVENT_RPC_RESPONSE`/`SPNEGO_AUTHEN_RESPONSE` attribute followed by a chosen nlattr header supplies both the undersized `sz` and the out-of-bounds \"handle\" value, and IDA-allocated handles are small and brute-forceable.\nPR:L - The `netlink_capable(CAP_NET_ADMIN)` gate exists only when `CONFIG_SMB_SERVER_CHECK_CAP_NET_ADMIN` is set, and builds that disable it let any unprivileged local user open a `NETLINK_GENERIC` socket and send the message; there is also no check binding the sender to the registered `ksmbd_tools_pid`.\nUI:N - The attacker sends the malformed netlink message directly; no victim action is needed beyond ksmbd already running, which is the normal state on an SMB server.\nS:U - The out-of-bounds read and the resulting fault stay within the kernel's own security authority, with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - The unchecked deref reads 4 bytes past the declared payload, and the undersized response it admits causes `ipc_validate_msg()` and the SPNEGO/RPC consumers to read fields beyond a tiny slab allocation, whose contents can be reflected back toward the SMB client.\nI:N - The `memcpy(entry->response, payload, sz)` is bounded by the same `sz` used for the allocation, so the bug yields no out-of-bounds write or other data-modification primitive.\nA:H - A zero-length payload makes `kvzalloc(0)` return `ZERO_SIZE_PTR`, which passes the non-NULL check and is then dereferenced in `ipc_validate_msg()`, producing a kernel oops that is repeatable at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/transport_ipc.c" ], "versions": [ { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "a02e432d5130da4c723aabe1205bac805889fdb2", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "2dc125f5da134c0915a840b62565c60a595673dd", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "898d527ed94c19980a4d848f10057f1fed578ffb", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "867ffd9d67285612da3f0498ca618297f8e41f01", "status": "affected", "versionType": "git" }, { "version": "0626e6641f6b467447c81dd7678a69c66f7746cf", "lessThan": "6f40e50ceb99fc8ef37e5c56e2ec1d162733fef0", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/smb/server/transport_ipc.c" ], "versions": [ { "version": "5.15", "status": "affected" }, { "version": "0", "lessThan": "5.15", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.158", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.115", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.56", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.6", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18", "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": "5.15", "versionEndExcluding": "6.1.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.6.115" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.12.56" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.17.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.15", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/a02e432d5130da4c723aabe1205bac805889fdb2" }, { "url": "https://git.kernel.org/stable/c/2dc125f5da134c0915a840b62565c60a595673dd" }, { "url": "https://git.kernel.org/stable/c/898d527ed94c19980a4d848f10057f1fed578ffb" }, { "url": "https://git.kernel.org/stable/c/867ffd9d67285612da3f0498ca618297f8e41f01" }, { "url": "https://git.kernel.org/stable/c/6f40e50ceb99fc8ef37e5c56e2ec1d162733fef0" } ], "title": "ksmbd: transport_ipc: validate payload size before reading handle", "x_generator": { "engine": "bippy-1.2.0" } } } }