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CVE-2026-74494— ksmbd: reject repeated SMB2 NEGOTIATE requests

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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于ksmbd在处理SMB2 NEGOTIATE请求时未正确拒绝重复请求，导致内存泄漏，可能允许未经身份验证的客户端通过发送多个成功请求导致拒绝服务。

AI Predicted 5.3 Difficulty: Easy EPSS 0.17% · P7

Affected Version Matrix 16

VendorProduct Version RangeStatus
Linux Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 0b1390cf2b6b91723b37c0909dd123f7a5eba1a7 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< fd6a6c43f96b40a08a22ff62f08d194a49741c8a affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 81e21cb7bd1479bb5238e0004a7e0110452c610b affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 7fb8dbeb3f2868ae836ca12311d89aed16fc2927 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< a60b5da05e318d9a364dbac38c347c7f24e625e7 affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< 7e02cb30e8a1f5fc78cb10b220b06020e36d0bbe affected
e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9< cb469993b3a61a72653770856d37af616d72d05f affected
5.15 affected
… +8 more rows
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I. Basic Information for CVE-2026-74494

Vulnerability Information
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Vulnerability Title
ksmbd: reject repeated SMB2 NEGOTIATE requests
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: reject repeated SMB2 NEGOTIATE requests Unauthenticated client can send multiple successful SMB2 NEGOTIATE requests on one connection before SESSION_SETUP. While the connection is in KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another SMB3.1.1 NEGOTIATE and overwrites conn->preauth_info with a new allocation. Only the final allocation is freed when the connection is released, leaking one object for every additional successful request. A repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol violation. MS-SMB2 section 3.3.5.4 requires the server to disconnect without replying in this case. Set the connection exiting when rejecting the request, in addition to suppressing the response. Reject SMB2 NEGOTIATE unless the connection is new or is waiting for the SMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize both SMB1 and SMB2 negotiation paths under conn->srv_mutex, since they update connection-wide dialect and negotiation state. Move the locking contract to ksmbd_smb_negotiate_common(), where the state and dialect are selected, and add ksmbd_conn_new() for consistent state access.
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基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于ksmbd在处理SMB2 NEGOTIATE请求时未正确拒绝重复请求，导致内存泄漏，可能允许未经身份验证的客户端通过发送多个成功请求导致拒绝服务。
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 e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 ~ 0b1390cf2b6b91723b37c0909dd123f7a5eba1a7 -
Linux Linux 5.15 -

II. Public POCs for CVE-2026-74494

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III. Intelligence Information for CVE-2026-74494

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Patches & Fixes for CVE-2026-74494 (7)

Same Patch Batch · Linux · 2026-08-15 · 845 CVEs total

CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72408 10.0 CRITICAL geneve: gate GRO hint in geneve_gro_complete() on gs->gro_hint
CVE-2026-72407 10.0 CRITICAL geneve: validate inner network offset in geneve_gro_complete()
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72221 9.8 CRITICAL sunrpc: wait for in-flight TLS handshake callback when cancel loses race
CVE-2026-72466 9.8 CRITICAL xprtrdma: Fix bcall rep leak and unbounded peek
CVE-2026-72323 9.8 CRITICAL ipv4: igmp: Fix potential UAF in igmp_gq_start_timer()
CVE-2026-72463 9.8 CRITICAL xfrm: Fix dev use-after-free in xfrm async resumption
CVE-2026-72069 9.8 CRITICAL locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()
CVE-2026-72339 9.8 CRITICAL qede: fix off-by-one in BD ring consumption on build_skb failure
CVE-2026-72065 9.8 CRITICAL net: mana: Validate the packet length reported by the NIC
CVE-2026-72064 9.8 CRITICAL net: mana: Sync page pool RX frags for CPU
CVE-2026-74255 9.8 CRITICAL tipc: fix UAF in tipc_l2_send_msg()
CVE-2026-74376 9.8 CRITICAL md/raid10: reset read_slot when reusing r10bio for discard
CVE-2026-74495 9.8 CRITICAL igbvf: Fix leak in TX DMA error cleanup
CVE-2026-72220 9.8 CRITICAL sunrpc: harden rq_procinfo lifecycle to prevent double-free

Showing top 20 of 845 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-74494

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