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CVE-2026-43421— usb: gadget: f_ncm: Fix net_device lifecycle with device_move

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usb gadget f_ncm驱动在断开连接时网络设备生命周期超过父设备，导致悬空sysfs链接和空指针取消引用。

AI Predicted 5.5 Difficulty: Moderate EPSS 0.16% · P5

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux 40d133d7f542616cf9538508a372306e626a16e9< 7c97366f5dac5255e60a317ffe3a5b18f3745547 affected
40d133d7f542616cf9538508a372306e626a16e9< 36c41e9724c9a7a7cda37f5a4e9d94f25c8031c4 affected
40d133d7f542616cf9538508a372306e626a16e9< 93f116c3393a22acab96ad1bef12b2572eb80ca4 affected
40d133d7f542616cf9538508a372306e626a16e9< e584cb58a2ea7ff4d3a4bc43d5ca512ed3ecb77d affected
40d133d7f542616cf9538508a372306e626a16e9< 85acaba2f42b557499bab3608307f17bf13beb69 affected
40d133d7f542616cf9538508a372306e626a16e9< ec35c1969650e7cb6c8a91020e568ed46e3551b0 affected
3.11 affected
< 3.11 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-43421

Vulnerability Information
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Vulnerability Title
usb: gadget: f_ncm: Fix net_device lifecycle with device_move
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ncm: Fix net_device lifecycle with device_move The network device outlived its parent gadget device during disconnection, resulting in dangling sysfs links and null pointer dereference problems. A prior attempt to solve this by removing SET_NETDEV_DEV entirely [1] was reverted due to power management ordering concerns and a NO-CARRIER regression. A subsequent attempt to defer net_device allocation to bind [2] broke 1:1 mapping between function instance and network device, making it impossible for configfs to report the resolved interface name. This results in a regression where the DHCP server fails on pmOS. Use device_move to reparent the net_device between the gadget device and /sys/devices/virtual/ across bind/unbind cycles. This preserves the network interface across USB reconnection, allowing the DHCP server to retain their binding. Introduce gether_attach_gadget()/gether_detach_gadget() helpers and use __free(detach_gadget) macro to undo attachment on bind failure. The bind_count ensures device_move executes only on the first bind. [1] https://lore.kernel.org/lkml/f2a4f9847617a0929d62025748384092e5f35cce.camel@crapouillou.net/ [2] https://lore.kernel.org/linux-usb/795ea759-7eaf-4f78-81f4-01ffbf2d7961@ixit.cz/
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usb gadget f_ncm驱动在断开连接时网络设备生命周期超过父设备，导致悬空sysfs链接和空指针取消引用。
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 40d133d7f542616cf9538508a372306e626a16e9 ~ 7c97366f5dac5255e60a317ffe3a5b18f3745547 -
Linux Linux 3.11 -

II. Public POCs for CVE-2026-43421

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III. Intelligence Information for CVE-2026-43421

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Patches & Fixes for CVE-2026-43421 (6)

Same Patch Batch · Linux · 2026-05-08 · 197 CVEs total

CVE-2026-43384 9.8 CRITICAL net/tcp-ao: Fix MAC comparison to be constant-time
CVE-2026-43341 9.8 CRITICAL net/ipv6: ioam6: prevent schema length wraparound in trace fill
CVE-2026-43304 9.8 CRITICAL libceph: define and enforce CEPH_MAX_KEY_LEN
CVE-2026-43379 9.8 CRITICAL ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()
CVE-2026-43378 9.8 CRITICAL smb: server: fix use-after-free in smb2_open()
CVE-2026-43465 9.8 CRITICAL net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
CVE-2026-43414 9.8 CRITICAL scsi: qla2xxx: Completely fix fcport double free
CVE-2026-43376 9.8 CRITICAL ksmbd: fix use-after-free by using call_rcu() for oplock_info
CVE-2026-43402 9.8 CRITICAL kthread: consolidate kthread exit paths to prevent use-after-free
CVE-2026-43383 9.4 CRITICAL net/tcp-md5: Fix MAC comparison to be constant-time
CVE-2026-43407 9.1 CRITICAL libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply()
CVE-2026-43406 9.1 CRITICAL libceph: prevent potential out-of-bounds reads in process_message_header()
CVE-2026-43284 8.8 HIGH xfrm: esp: avoid in-place decrypt on shared skb frags
CVE-2026-43334 8.8 HIGH Bluetooth: SMP: force responder MITM requirements before building the pairing response
CVE-2026-43322 8.8 HIGH Bluetooth: hci_sync: Fix UAF in le_read_features_complete
CVE-2026-43403 8.8 HIGH nsfs: tighten permission checks for ns iteration ioctls
CVE-2026-43391 8.8 HIGH nsfs: tighten permission checks for handle opening
CVE-2026-43291 8.3 HIGH net: nfc: nci: Fix parameter validation for packet data
CVE-2026-43466 8.2 HIGH net/mlx5e: Fix DMA FIFO desync on error CQE SQ recovery
CVE-2026-43365 8.2 HIGH xfs: fix undersized l_iclog_roundoff values

Showing top 20 of 197 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-43421

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