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CVE-2026-90174— ksmbd: fix slab-out-of-bounds read in ksmbd_alloc_user()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，已修复以下漏洞： ksmbd：修复 ksmbd_alloc_user() 中的堆越界读（slab-out-of-bounds read） 函数会从 mountd IPC 登录响应中拷贝 字节的数据，代码如下： 其中， 是一个由响应端提供的 类型字段，但 缓冲区的大小仅为 字节。如果收到格式错误或恶意的登录响应， 可能被设置为远大于该缓冲区上限的值（最大可达 65535），从而导致 读取超出响应对象末尾的内存。而 函数并未对 进行边界检查，因此需要在分配和拷贝之前，拒绝任何 超过栈上 缓冲区大

CVSS 7.1 · High EPSS 0.16% · P4

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 497c221bf6b2f659511719a6acfae84cc1be1caf affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 7405d0ba294306721843bc551611775e6edef516 affected
5.15 affected
< 5.15 unaffected
7.2.6≤ 7.2.* unaffected
7.3-rc1≤ * unaffected
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I. Basic Information for CVE-2026-90174

Vulnerability Information
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Vulnerability Title
ksmbd: fix slab-out-of-bounds read in ksmbd_alloc_user()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix slab-out-of-bounds read in ksmbd_alloc_user() ksmbd_alloc_user() copies resp->hash_sz bytes out of the mountd IPC login response with user->passkey_sz = resp->hash_sz; user->passkey = kmalloc(resp->hash_sz, KSMBD_DEFAULT_GFP); if (user->passkey) memcpy(user->passkey, resp->hash, resp->hash_sz); resp->hash_sz is a __u16 supplied by the response, but resp->hash[] is only KSMBD_REQ_MAX_HASH_SZ bytes. A malformed or malicious login response can set hash_sz well beyond that (up to 65535), so the memcpy() reads past the end of the response object. ipc_validate_msg() does not bound hash_sz, so reject any response whose hash_sz exceeds the on-stack hash[] buffer before allocating and copying. [ 2030.238706] BUG: KASAN: slab-out-of-bounds in ksmbd_alloc_user+0x278/0x680 [ 2030.240549] Read of size 65535 at addr ffff888121bb6680 by task kworker/4:1/18611 [ 2030.242296] [ 2030.242710] CPU: 4 UID: 0 PID: 18611 Comm: kworker/4:1 Not tainted 7.1.0-next-20260623-virtme #96 PREEMPT(lazy) [ 2030.242732] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 [ 2030.242743] Workqueue: ksmbd-io handle_ksmbd_work [ 2030.242763] Call Trace: [ 2030.242769] <TASK> [ 2030.242776] dump_stack_lvl+0xa2/0xd0 [ 2030.242794] print_address_description+0x77/0x200 [ 2030.242815] ? ksmbd_alloc_user+0x278/0x680 [ 2030.242831] print_report+0x58/0x70 [ 2030.242848] kasan_report+0x117/0x150 [ 2030.242869] ? ksmbd_alloc_user+0x278/0x680 [ 2030.242888] kasan_check_range+0x3c7/0x3f0 [ 2030.242908] ? ksmbd_alloc_user+0x278/0x680 [ 2030.242925] __asan_memcpy+0x29/0x70 [ 2030.242942] ksmbd_alloc_user+0x278/0x680 [ 2030.242960] ksmbd_login_user+0xc3/0x120 [ 2030.242978] ntlm_authenticate+0x5e6/0x1b00 [ 2030.243017] ? __pfx_ntlm_authenticate+0x10/0x10 [ 2030.243035] ? ksmbd_session_lookup+0x188/0x1d0 [ 2030.243054] ? __pfx_ksmbd_session_lookup+0x10/0x10 [ 2030.243090] ? __sanitizer_cov_trace_switch+0x7b/0x140 [ 2030.243108] smb2_sess_setup+0x1e4a/0x27b0 [ 2030.243126] ? copy_from_kernel_nofault+0x199/0x300 [ 2030.243156] ? __pfx_smb2_sess_setup+0x10/0x10 [ 2030.243173] ? get_smb2_cmd_val+0xe3/0x1c0 [ 2030.243208] handle_ksmbd_work+0x954/0x1280 [ 2030.243230] ? __pfx_handle_ksmbd_work+0x10/0x10 [ 2030.243249] ? process_scheduled_works+0xa07/0x1490 [ 2030.243270] ? process_scheduled_works+0xa07/0x1490 [ 2030.243291] process_scheduled_works+0xa70/0x1490 [ 2030.243320] ? __pfx_process_scheduled_works+0x10/0x10 [ 2030.243340] ? do_raw_spin_lock+0x130/0x300 [ 2030.243358] ? lock_is_held_type+0x7b/0x110 [ 2030.243388] worker_thread+0x932/0xe20 [ 2030.243415] kthread+0x38a/0x470 [ 2030.243431] ? __pfx_worker_thread+0x10/0x10 [ 2030.243451] ? __pfx_kthread+0x10/0x10 [ 2030.243467] ret_from_fork+0x484/0x910 [ 2030.243485] ? __pfx_ret_from_fork+0x10/0x10 [ 2030.243501] ? __switch_to+0xc77/0x12c0 [ 2030.243523] ? __pfx_kthread+0x10/0x10 [ 2030.243540] ret_from_fork_asm+0x1a/0x30 [ 2030.243564] </TASK> [ 2030.243570] [ 2030.290164] Allocated by task 19279: [ 2030.290911] kasan_save_track+0x3e/0x80 [ 2030.292179] __kasan_kmalloc+0x72/0x90 [ 2030.293217] __kvmalloc_node_noprof+0x3ff/0x6b0 [ 2030.294467] handle_generic_event+0x59b/0x750 [ 2030.295345] genl_family_rcv_msg_doit+0x238/0x340 [ 2030.296553] genl_rcv_msg+0x606/0x7b0 [ 2030.297129] netlink_rcv_skb+0x22b/0x4a0 [ 2030.298500] genl_rcv+0x2d/0x40 [ 2030.299273] netlink_unicast+0x7ba/0x930 [ 2030.300019] netlink_sendmsg+0x8c3/0xb00 [ 2030.301073] __sock_sendmsg+0xec/0x140 [ 2030.301579] __sys_sendto+0x357/0x470 [ 2030.302255] __x64_sys_sendto+0xe3/0x100 [ 2030.303425] do_syscall_64+0x135/0x460 [ 2030.304763] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 2030.305594] [ 2030.305819] The buggy address belongs to the object at ffff888121bb6640 [ 2030.305819] which belongs to the cache kmalloc-192 of size 192 [ 2030.309595] The buggy address ---truncated---
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 ~ 497c221bf6b2f659511719a6acfae84cc1be1caf -
Linux Linux 5.15 -

II. Public POCs for CVE-2026-90174

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III. Intelligence Information for CVE-2026-90174

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Patches & Fixes for CVE-2026-90174 (2)

Same Patch Batch · Linux · 2026-09-17 · 600 CVEs total

CVE-2026-92489 9.8 CRITICAL xfrm: Fix skb double-free in xfrm_dev_direct_output()
CVE-2026-90104 9.8 CRITICAL NFSv4.1: zero referring call lists before decoding
CVE-2026-90235 9.8 CRITICAL sunrpc: xprtsock: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
CVE-2026-90173 9.8 CRITICAL smb: smbdirect: free completion queues with ib_free_cq()
CVE-2026-90151 9.8 CRITICAL NFSv4: remove callback IDR entry on client allocation failure
CVE-2026-90110 9.4 CRITICAL inetpeer: randomize RB-tree node comparison using SipHash
CVE-2026-90413 9.1 CRITICAL IB/isert: reject login PDUs declaring more data than was received
CVE-2026-90414 9.1 CRITICAL IB/isert: reject PDUs declaring more data than was received
CVE-2026-90230 9.1 CRITICAL nvmet: fix heap out-of-bounds read in nvmet_auth_negotiate()
CVE-2026-90256 8.8 HIGH Bluetooth: L2CAP: use proto_lock for l2cap_data to fix l2cap_disconn_ind
CVE-2026-90357 8.8 HIGH wifi: mt76: mt7915: unlink TWT flow if the MCU rejects the agreement
CVE-2026-90286 8.8 HIGH drm/amdgpu/gfx6: Use PFP on the compute queues too
CVE-2026-90381 8.8 HIGH wifi: mt76: fix handling channel context with different bands in mt76_switch_vif_chanctx()
CVE-2026-90380 8.8 HIGH wifi: mt76: mt792x: fix use-after-free in mt76_rx_poll_complete
CVE-2026-90329 8.8 HIGH HID: synchronize input before cleaning up a failed probe
CVE-2026-93042 8.8 HIGH dmaengine: dw-edma: Terminate all descriptors without callbacks
CVE-2026-90162 8.8 HIGH ksmbd: defer publishing granted locks to prevent UAF/double-free race
CVE-2026-90379 8.8 HIGH wifi: mt76: mt7921: Add PCIe AER handler support to prevent system crash
CVE-2026-90367 8.8 HIGH wifi: mt76: mt7996: hold dev->mt76.mutex while disabling tx worker in SER
CVE-2026-90371 8.8 HIGH wifi: mt76: fix RXDMAD_C buffer recycling race

Showing top 20 of 600 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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