{"id":"CVE-2026-64578","published":"2026-08-05T08:16:37.760","lastModified":"2026-08-08T15:16:32.803","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: validate compound request size before reading StructureSize2\n\nWhen ksmbd validates a compound (chained) SMB2 request,\nksmbd_smb2_check_message() reads pdu->StructureSize2 without first\nchecking that the compound element is large enough to contain it.\nStructureSize2 is a 2-byte field at offset 64\n(__SMB2_HEADER_STRUCTURE_SIZE) from the start of each element.\n\nThe compound-walking logic only guarantees that a full 64-byte SMB2\nheader is present for the trailing element: when NextCommand is 0, len is\nreduced to the number of bytes remaining after next_smb2_rcv_hdr_off. A\nremote client can craft a compound request whose last element has exactly\n64 bytes, so the 2-byte StructureSize2 read at offset 64 extends one byte\npast the receive buffer, producing a slab-out-of-bounds read.\n\n  BUG: KASAN: slab-out-of-bounds in ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402)\n  Read of size 2 at addr ffff888012ae31ac by task kworker/0:1/14\n  The buggy address is located 172 bytes inside of allocated 173-byte region\n  Workqueue: ksmbd-io handle_ksmbd_work\n  Call Trace:\n   ...\n   kasan_report (mm/kasan/report.c:595)\n   ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402)\n   handle_ksmbd_work (fs/smb/server/server.c:119)\n   process_one_work (kernel/workqueue.c:3314)\n   worker_thread (kernel/workqueue.c:3397)\n   kthread (kernel/kthread.c:436)\n   ret_from_fork (arch/x86/kernel/process.c:158)\n   ret_from_fork_asm (arch/x86/entry/entry_64.S:245)\n\nReject any compound element that is too small to hold StructureSize2\nbefore dereferencing it.","cvssScore":8.2,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/15b38176fd1530372905c602fde51fe89ec8c877","tags":[]},{"url":"https://git.kernel.org/stable/c/2c307126ed8e7adddab82b8e31d962d3a2156ab1","tags":[]},{"url":"https://git.kernel.org/stable/c/ea128f06d2fb2186f0cac0c9f3e953e4d1f5c29a","tags":[]},{"url":"https://git.kernel.org/stable/c/f0e337e7db67cc1c832958bbb6c4026bdceacfdb","tags":[]},{"url":"https://git.kernel.org/stable/c/f7550a91ab211726f59cb137523b7a9eae1ac6eb","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"This flaw allows a remote client to read out-of-bounds data by crafting a compound SMB2 request with an improperly sized StructureSize2 field, potentially leading to information disclosure.","exploitability":"Exploitation requires precise crafting of the SMB2 request and access to the affected system; it is moderately difficult but not trivial.","blast_radius":"If exploited, this could lead to sensitive data exposure on the Linux kernel hosting the ksmbd service.","remediation":"Update to the latest patched version of the Linux kernel as soon as possible.","tags":["info-disc","smb","kernel"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-08-11T06:49:22.917Z"}}