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CVE-2026-43455— mctp: route: hold key->lock in mctp_flow_prepare_output()

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mctp route组件中mctp_flow_prepare_output函数未持有key->lock锁，导致key->dev的检查和设置序列存在竞争条件。

AI Predicted 3.7 Difficulty: Moderate EPSS 0.16% · P5

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux 67737c457281dd199ceb9e31b6ba7efd3bfe566d< 47893166bc5611ee9a20de6b8d2933b2320fb772 affected
67737c457281dd199ceb9e31b6ba7efd3bfe566d< 86f5334fcb48a5b611c33364ab52ca684d0f6d91 affected
67737c457281dd199ceb9e31b6ba7efd3bfe566d< 0695712f3a6f1a48915f95767cfb42077683dcdc affected
67737c457281dd199ceb9e31b6ba7efd3bfe566d< 925a5ffd99cddd7a7e41d5ad120c7a2c6d50260f affected
67737c457281dd199ceb9e31b6ba7efd3bfe566d< 8d27d9b260dd19c1b519e1a13de6448f9984e30e affected
67737c457281dd199ceb9e31b6ba7efd3bfe566d< 7d86aa41c073c4e7eb75fd2e674f1fd8f289728a affected
5.16 affected
< 5.16 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-43455

Vulnerability Information
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Vulnerability Title
mctp: route: hold key->lock in mctp_flow_prepare_output()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: mctp: route: hold key->lock in mctp_flow_prepare_output() mctp_flow_prepare_output() checks key->dev and may call mctp_dev_set_key(), but it does not hold key->lock while doing so. mctp_dev_set_key() and mctp_dev_release_key() are annotated with __must_hold(&key->lock), so key->dev access is intended to be serialized by key->lock. The mctp_sendmsg() transmit path reaches mctp_flow_prepare_output() via mctp_local_output() -> mctp_dst_output() without holding key->lock, so the check-and-set sequence is racy. Example interleaving: CPU0 CPU1 ---- ---- mctp_flow_prepare_output(key, devA) if (!key->dev) // sees NULL mctp_flow_prepare_output( key, devB) if (!key->dev) // still NULL mctp_dev_set_key(devB, key) mctp_dev_hold(devB) key->dev = devB mctp_dev_set_key(devA, key) mctp_dev_hold(devA) key->dev = devA // overwrites devB Now both devA and devB references were acquired, but only the final key->dev value is tracked for release. One reference can be lost, causing a resource leak as mctp_dev_release_key() would only decrease the reference on one dev. Fix by taking key->lock around the key->dev check and mctp_dev_set_key() call.
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mctp route组件中mctp_flow_prepare_output函数未持有key->lock锁，导致key->dev的检查和设置序列存在竞争条件。
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 67737c457281dd199ceb9e31b6ba7efd3bfe566d ~ 47893166bc5611ee9a20de6b8d2933b2320fb772 -
Linux Linux 5.16 -

II. Public POCs for CVE-2026-43455

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III. Intelligence Information for CVE-2026-43455

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Patches & Fixes for CVE-2026-43455 (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-2026-43304 9.8 CRITICAL libceph: define and enforce CEPH_MAX_KEY_LEN
CVE-2026-43341 9.8 CRITICAL net/ipv6: ioam6: prevent schema length wraparound in trace fill
CVE-2026-43465 9.8 CRITICAL net/mlx5e: RX, Fix XDP multi-buf frag counting for striding RQ
CVE-2026-43376 9.8 CRITICAL ksmbd: fix use-after-free by using call_rcu() for oplock_info
CVE-2026-43378 9.8 CRITICAL smb: server: fix use-after-free in smb2_open()
CVE-2026-43414 9.8 CRITICAL scsi: qla2xxx: Completely fix fcport double free
CVE-2026-43379 9.8 CRITICAL ksmbd: fix use-after-free in smb_lazy_parent_lease_break_close()
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-2026-43322 8.8 HIGH Bluetooth: hci_sync: Fix UAF in le_read_features_complete
CVE-2026-43284 8.8 HIGH xfrm: esp: avoid in-place decrypt on shared skb frags
CVE-2026-43403 8.8 HIGH nsfs: tighten permission checks for ns iteration ioctls
CVE-2026-43334 8.8 HIGH Bluetooth: SMP: force responder MITM requirements before building the pairing response
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-2026-43455

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