CVE-2026-90170
Low risk· EPSS 10%Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
In the Linux kernel's ksmbd module, ipc_validate_msg() reads length fields (payload_sz, session_key_len, ngroups) from the response buffer supplied by the userspace ksmbd daemon before verifying the buffer is large enough. A short response causes an out-of-bounds read past the end of the allocation, triggering a KASAN slab-out-of-bounds error.
Risk Assessment
A local attacker or a malicious/misbehaving ksmbd daemon can trigger an out-of-bounds read in kernel memory, potentially leading to information disclosure, system crash (panic), or further privilege escalation.
Recommendation
Update the Linux kernel to a version containing the fix that validates the IPC response length before dereferencing its fields. If updating is not possible, restrict access to the ksmbd service to trusted clients.
Other vulnerabilities in Linux kernel (ksmbd)
See all- CVE-2026-89788Critical
In the Linux kernel, the ksmbd module contains a use-after-free vulnerability in smb2_tree_connect(). A newly created tree connection is published in the session and then used by the handler, while a concurrent session logoff can free the object before the handler finishes.
- CVE-2026-89635Critical
In the Linux kernel, the ksmbd_reopen_durable_fd() function rebinds every detached oplock on an inode to the reconnecting session instead of only the oplock owned by the reopened file. This allows one session to adopt another session's oplock, and when the adopting session is destroyed, a use-after-free occurs. The vulnerability is reachable with the default durable-handle and oplock configuration when two sessions open the same file with distinct AppInstanceIds.
- CVE-2026-80926Critical
A use-after-free vulnerability was fixed in the Linux kernel's ksmbd oplock break notification mechanism. The smb2_oplock_break_noti() function read the opinfo->conn pointer without locking and dereferenced it after sleeping allocations, allowing a race with durable handle teardown to access a freed connection. The flaw is reachable by any authenticated client holding a durable batch oplock.
- CVE-2026-43376Critical
A vulnerability has been identified in the Linux kernel within ksmbd, related to a use-after-free error due to immediate freeing of the oplock_info structure. This issue occurs when the pointer is nullified without a grace period delay in RCU, allowing access to already freed memory.
- CVE-2026-43185Critical
The ksmbd module in the Linux kernel has a signedness bug in smb_direct_prepare_negotiation(). An unsigned __u32 value from preferred_send_size is cast to a signed int before computing min_t(int, ...), so a malicious value of 0x80000000 is treated as smaller than max_recv_size and used to set the maximum allowed receive size. By sending a second message with a large value (>1420 bytes), the attacker can achieve a heap buffer overflow.
- CVE-2026-23428Critical
A use-after-free vulnerability exists in the Linux kernel ksmbd module involving the share_conf object in compound requests. smb2_get_ksmbd_tcon() reuses work->tcon without validating tcon->t_state, so after an earlier SMB2_TREE_DISCONNECT frees share_conf, subsequent commands dereference the freed memory.
- CVE-2023-54203Critical
In the Linux kernel, a vulnerability in the ksmbd module leads to a slab-out-of-bounds read in the init_smb2_rsp_hdr function. The issue occurs when an SMB1 mount attempt fails and the ksmbd server incorrectly handles SMB1 negotiation as an SMB2 operation, causing an out-of-bounds memory read.
- CVE-2023-38432Critical
An issue was discovered in the Linux kernel before 6.3.10 related to the validation of command payload size in ksmbd, leading to an out-of-bounds read.
- CVE-2023-38431Critical
An issue was discovered in the Linux kernel before 6.3.8 related to the lack of validation of the NetBIOS header's length in relation to SMB header sizes in ksmbd. This leads to an out-of-bounds read.
- CVE-2023-38427Critical
An issue was discovered in the Linux kernel before 6.3.8 related to integer underflow and out-of-bounds read in the deassemble_neg_contexts function in fs/smb/server/smb2pdu.c in ksmbd.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate ipc response length before dereferencing its fields ipc_validate_msg() computes the expected message size by reading length fields out of the response buffer supplied by the userspace ksmbd daemon (payload_sz, session_key_len, ngroups, ...). Those fields are read before the buffer is verified to be large enough to contain the struct they belong to, so a short response makes the read land past the end of the allocation. handle_response() sizes entry->response purely from the netlink attribute length (nla_len()) and only guards the leading handle read, so the daemon can install a response as small as the kmalloc-8 object seen below. When ipc_msg_send_request() then calls ipc_validate_msg() for a KSMBD_EVENT_RPC_REQUEST, the cast to struct ksmbd_rpc_command reads resp->payload_sz at offset 8 of an 8-byte allocation: [ 3697.841381] ================================================================== [ 3697.844099] BUG: KASAN: slab-out-of-bounds in ipc_msg_send_request+0x763/0x800 [ 3697.846604] Read of size 4 at addr ffff888105f95910 by task kworker/4:3/20682 [ 3697.849061] [ 3697.849801] CPU: 4 UID: 0 PID: 20682 Comm: kworker/4:3 Not tainted 7.2.0-rc3-next-20260717-virtme #117 PREEMPT(lazy) [ 3697.850077] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 [ 3697.850303] Workqueue: ksmbd-io handle_ksmbd_work [ 3697.850592] Call Trace: [ 3697.850794] <TASK> [ 3697.850952] __dump_stack+0x21/0x60 [ 3697.851239] dump_stack_lvl+0xc2/0x100 [ 3697.851528] print_address_description+0x77/0x200 [ 3697.851816] ? ipc_msg_send_request+0x763/0x800 [ 3697.852024] print_report+0x58/0x70 [ 3697.852316] kasan_report+0x117/0x150 [ 3697.852585] ? down_write+0x146/0x1f0 [ 3697.852809] ? ipc_msg_send_request+0x763/0x800 [ 3697.853082] ipc_msg_send_request+0x763/0x800 [ 3697.853385] ? __pfx_ipc_msg_send_request+0x10/0x10 [ 3697.853604] ? kasan_unpoison+0x48/0x70 [ 3697.853936] ? __pfx___up_read+0x10/0x10 [ 3697.854221] ksmbd_rpc_ioctl+0x380/0x520 [ 3697.854542] ? __pfx_ksmbd_rpc_ioctl+0x10/0x10 [ 3697.854757] ? kasan_unpoison+0x48/0x70 [ 3697.854962] ? copy_from_kernel_nofault+0x32c/0x4e0 [ 3697.855166] ? kasan_unpoison+0x48/0x70 [ 3697.855416] fsctl_pipe_transceive+0x139/0x7a0 [ 3697.855705] ? __pfx_copy_from_kernel_nofault+0x10/0x10 [ 3697.855937] ? __pfx_fsctl_pipe_transceive+0x10/0x10 [ 3697.856388] ? __sanitizer_cov_trace_switch+0x7b/0x140 [ 3697.856620] smb2_ioctl+0x1141/0x3420 [ 3697.856994] ? __pfx_smb2_ioctl+0x10/0x10 [ 3697.857182] ? get_smb2_cmd_val+0xe3/0x1c0 [ 3697.857655] handle_ksmbd_work+0x9ad/0x15e0 [ 3697.858034] ? __pfx_handle_ksmbd_work+0x10/0x10 [ 3697.858251] ? lock_release+0xf7/0x360 [ 3697.858466] ? process_scheduled_works+0x954/0x1600 [ 3697.858698] ? process_scheduled_works+0x954/0x1600 [ 3697.858905] process_scheduled_works+0xc22/0x1600 [ 3697.859368] ? __pfx_process_scheduled_works+0x10/0x10 [ 3697.859637] ? __pfx_assign_work+0x10/0x10 [ 3697.859896] ? lock_is_held_type+0x7b/0x110 [ 3697.860146] worker_thread+0x975/0xee0 [ 3697.860524] ? __pfx_do_raw_spin_lock+0x10/0x10 [ 3697.860830] ? __kthread_parkme+0x21e/0x260 [ 3697.861105] kthread+0x3a6/0x490 [ 3697.861423] ? __pfx_worker_thread+0x10/0x10 [ 3697.861643] ? __pfx_kthread+0x10/0x10 [ 3697.861878] ret_from_fork+0x55a/0xa20 [ 3697.862194] ? __pfx_ret_from_fork+0x10/0x10 [ 3697.862480] ? __pfx_kthread+0x10/0x10 [ 3697.862714] ret_from_fork_asm+0x1a/0x30 [ 3697.862965] </TASK> [ 3697.863039] [ 3697.938882] Allocated by task 20761: [ 3697.940257] kasan_save_track+0x3e/0x80 [ 3697.941782] __kasan_kmalloc+0x72/0x90 [ 3697.943228] __kvmalloc_node_noprof+0x3e9/0x6a0 [ 3697.944948] handle_generic_event+0x59b/0x750 [ 3697.946592] genl_family_rcv_msg_doit+0x3d6/0x560 [ 3697.946977] genl_rcv_msg+0x67c/0x900 [ 3697.947224] netlink_rcv_skb+0x286/0x580 [ 3697.947488] genl_rcv+0x2d/0x80 [ 3 ---truncated---
Vulnerability data from NVD (NIST) · CISA KEV · EPSS