CVE-2026-64578

CVE CVE-2026-64578EUVD EUVD-2026-53272Published 2026-08-05T08:09:33.000ZLast changed 2026-08-08T15:13:16.000ZCVSS 8.2

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate compound request size before reading StructureSize2 When ksmbd validates a compound (chained) SMB2 request, ksmbd_smb2_check_message() reads pdu->StructureSize2 without first checking that the compound element is large enough to contain it. StructureSize2 is a 2-byte field at offset 64 (__SMB2_HEADER_STRUCTURE_SIZE) from the start of each element. The compound-walking logic only guarantees that a full 64-byte SMB2 header is present for the trailing element: when NextCommand is 0, len is reduced to the number of bytes remaining after next_smb2_rcv_hdr_off. A remote client can craft a compound request whose last element has exactly 64 bytes, so the 2-byte StructureSize2 read at offset 64 extends one byte past the receive buffer, producing a slab-out-of-bounds read. BUG: KASAN: slab-out-of-bounds in ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402) Read of size 2 at addr ffff888012ae31ac by task kworker/0:1/14 The buggy address is located 172 bytes inside of allocated 173-byte region Workqueue: ksmbd-io handle_ksmbd_work Call Trace: ... kasan_report (mm/kasan/report.c:595) ksmbd_smb2_check_message (fs/smb/server/smb2misc.c:402) handle_ksmbd_work (fs/smb/server/server.c:119) process_one_work (kernel/workqueue.c:3314) worker_thread (kernel/workqueue.c:3397) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) ret_from_fork_asm (arch/x86/entry/entry_64.S:245) Reject any compound element that is too small to hold StructureSize2 before dereferencing it.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux patch: 0; 5.15; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <2c307126ed8e7adddab82b8e31d962d3a2156ab1; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <ea128f06d2fb2186f0cac0c9f3e953e4d1f5c29a; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <f0e337e7db67cc1c832958bbb6c4026bdceacfdb; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <f7550a91ab211726f59cb137523b7a9eae1ac6eb; patch: 7.2-rc4; patch: 6.12.101; patch: 7.1.6; patch: 6.18.42; e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <15b38176fd1530372905c602fde51fe89ec8c877; patch: 6.6.148

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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