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CVE-2025-40084 (GCVE-0-2025-40084)

Vulnerability from cvelistv5 – Published: 2025-10-29 13:37 – Updated: 2026-08-05 12:07
VLAI
Title
ksmbd: transport_ipc: validate payload size before reading handle
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: transport_ipc: validate payload size before reading handle handle_response() dereferences the payload as a 4-byte handle without verifying that the declared payload size is at least 4 bytes. A malformed or truncated message from ksmbd.mountd can lead to a 4-byte read past the declared payload size. Validate the size before dereferencing. This is a minimal fix to guard the initial handle read.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < a02e432d5130da4c723aabe1205bac805889fdb2 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 2dc125f5da134c0915a840b62565c60a595673dd (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 898d527ed94c19980a4d848f10057f1fed578ffb (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 867ffd9d67285612da3f0498ca618297f8e41f01 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 6f40e50ceb99fc8ef37e5c56e2ec1d162733fef0 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 6.1.158 , ≤ 6.1.* (semver)
Unaffected: 6.6.115 , ≤ 6.6.* (semver)
Unaffected: 6.12.56 , ≤ 6.12.* (semver)
Unaffected: 6.17.6 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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          "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."
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              "value": "AV:L - The vulnerable code is reached only via a generic netlink message to the `SMBD_GENL` family (`handle_generic_event` \u2192 `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 \u2014 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\u0027s 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-\u003eresponse, 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."
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    "dateReserved": "2025-04-16T07:20:57.161Z",
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      "title": "kernel: ksmbd: transport_ipc: validate payload size before reading handle",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40084.json",
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      "cve": "CVE-2025-40084",
      "id": "CVE-2025-40084",
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      "title": "SUSE CVE CVE-2025-40084",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40084.json",
      "version": "8"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


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