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CVE-2026-23327— cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()

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.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于访问有效载荷内容前未验证其大小，可能导致越界读取。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.12% · P2

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux 6179045ccc0c6229dc449afc1701dc7fbd40571f< dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61 affected
6179045ccc0c6229dc449afc1701dc7fbd40571f< 7c8a7b7f063b7e7ae9bba4cbaa14a5d2fe3a55e1 affected
6179045ccc0c6229dc449afc1701dc7fbd40571f< 60b5d1f68338aff2c5af0113f04aefa7169c50c2 affected
5.19 affected
< 5.19 unaffected
6.18.34≤ 6.18.* unaffected
6.19.7≤ 6.19.* unaffected
7.0≤ * unaffected
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I. Basic Information for CVE-2026-23327

Vulnerability Information
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Vulnerability Title
cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: cxl/mbox: validate payload size before accessing contents in cxl_payload_from_user_allowed() cxl_payload_from_user_allowed() casts and dereferences the input payload without first verifying its size. When a raw mailbox command is sent with an undersized payload (ie: 1 byte for CXL_MBOX_OP_CLEAR_LOG, which expects a 16-byte UUID), uuid_equal() reads past the allocated buffer, triggering a KASAN splat: BUG: KASAN: slab-out-of-bounds in memcmp+0x176/0x1d0 lib/string.c:683 Read of size 8 at addr ffff88810130f5c0 by task syz.1.62/2258 CPU: 2 UID: 0 PID: 2258 Comm: syz.1.62 Not tainted 6.19.0-dirty #3 PREEMPT(voluntary) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xab/0xe0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xce/0x650 mm/kasan/report.c:482 kasan_report+0xce/0x100 mm/kasan/report.c:595 memcmp+0x176/0x1d0 lib/string.c:683 uuid_equal include/linux/uuid.h:73 [inline] cxl_payload_from_user_allowed drivers/cxl/core/mbox.c:345 [inline] cxl_mbox_cmd_ctor drivers/cxl/core/mbox.c:368 [inline] cxl_validate_cmd_from_user drivers/cxl/core/mbox.c:522 [inline] cxl_send_cmd+0x9c0/0xb50 drivers/cxl/core/mbox.c:643 __cxl_memdev_ioctl drivers/cxl/core/memdev.c:698 [inline] cxl_memdev_ioctl+0x14f/0x190 drivers/cxl/core/memdev.c:713 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa8/0x330 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fdaf331ba79 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdaf1d77038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fdaf3585fa0 RCX: 00007fdaf331ba79 RDX: 00002000000001c0 RSI: 00000000c030ce02 RDI: 0000000000000003 RBP: 00007fdaf33749df R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fdaf3586038 R14: 00007fdaf3585fa0 R15: 00007ffced2af768 </TASK> Add 'in_size' parameter to cxl_payload_from_user_allowed() and validate the payload is large enough.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于访问有效载荷内容前未验证其大小，可能导致越界读取。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 6179045ccc0c6229dc449afc1701dc7fbd40571f ~ dc184ac2f0ba77ae19725ee06ad3ab36bb9d1f61 -
Linux Linux 5.19 -

II. Public POCs for CVE-2026-23327

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III. Intelligence Information for CVE-2026-23327

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Patches & Fixes for CVE-2026-23327 (3)

Same Patch Batch · Linux · 2026-03-25 · 116 CVEs total

CVE-2026-23395 8.8 HIGH Bluetooth: L2CAP: Fix accepting multiple L2CAP_ECRED_CONN_REQ
CVE-2026-31788 8.2 HIGH xen/privcmd: restrict usage in unprivileged domU
CVE-2026-23280 7.8 HIGH accel/amdxdna: Prevent ubuf size overflow
CVE-2026-23317 7.8 HIGH drm/vmwgfx: Return the correct value in vmw_translate_ptr functions
CVE-2026-23393 7.8 HIGH bridge: cfm: Fix race condition in peer_mep deletion
CVE-2026-23392 7.8 HIGH netfilter: nf_tables: release flowtable after rcu grace period on error
CVE-2026-23391 7.8 HIGH netfilter: xt_CT: drop pending enqueued packets on template removal
CVE-2026-23340 7.8 HIGH net: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs
CVE-2026-23306 7.8 HIGH scsi: pm8001: Fix use-after-free in pm8001_queue_command()
CVE-2026-23372 7.8 HIGH nfc: rawsock: cancel tx_work before socket teardown
CVE-2026-23288 7.8 HIGH accel/amdxdna: Fix out-of-bounds memset in command slot handling
CVE-2026-23378 7.8 HIGH net/sched: act_ife: Fix metalist update behavior
CVE-2026-23336 7.8 HIGH wifi: cfg80211: cancel rfkill_block work in wiphy_unregister()
CVE-2026-23351 7.8 HIGH netfilter: nft_set_pipapo: split gc into unlink and reclaim phase
CVE-2026-23383 7.8 HIGH bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
CVE-2026-23350 7.8 HIGH drm/xe/queue: Call fini on exec queue creation fail
CVE-2026-23364 7.4 HIGH ksmbd: Compare MACs in constant time
CVE-2026-23294 7.0 HIGH bpf: Fix race in devmap on PREEMPT_RT
CVE-2026-23358 drm/amdgpu: Fix error handling in slot reset
CVE-2026-23357 can: mcp251x: fix deadlock in error path of mcp251x_open

Showing top 20 of 116 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23327

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