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CVE-2026-72422— ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE

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，该漏洞源于并发SMB2 NEGOTIATE请求时对conn->preauth_info的释放后重用，可能导致释放后重用攻击。

CVSS 9.8 · Critical EPSS 0.72% · P53

Possible ATT&CK Techniques 1 AI

T1068 · Exploitation for Privilege Escalation

Affected Version Matrix 21

VendorProduct Version RangeStatus
Linux Linux dd4e4c811898410e6a3ae3b63207b7c542860907< c7bef84740d1d57848c74f6f5b996606e43ea4fe affected
aa7253c2393f6dcd6a1468b0792f6da76edad917< d0a469122e7bf8338fec1949fb1e8e1290ed8caa affected
aa7253c2393f6dcd6a1468b0792f6da76edad917< 7470511d085af1c7a043a60e53d52b512d5a10b1 affected
aa7253c2393f6dcd6a1468b0792f6da76edad917< 16a1ecf39c217e3d164bd32ef2a4f650abc067fa affected
aa7253c2393f6dcd6a1468b0792f6da76edad917< 77bb0bbfcc4e777ca653174689e5e363f8ee63d1 affected
aa7253c2393f6dcd6a1468b0792f6da76edad917< 1c89da3baa2b1f269178afa87dc30479b8535776 affected
aa7253c2393f6dcd6a1468b0792f6da76edad917< 0c054227479ed7e36ebccb3a558bc0ef698264f6 affected
8a8315a5960bd2b5ffc75f44fc089e57c3b17c44 affected
… +13 more rows
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I. Basic Information for CVE-2026-72422

Vulnerability Information
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Vulnerability Title
ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free of conn->preauth_info in concurrent SMB2 NEGOTIATE conn->preauth_info is shared connection state (struct preauth_integrity_info, kmalloc-96) that is allocated and freed by the SMB2 NEGOTIATE handler and read by the response send path. smb2_handle_negotiate() allocates conn->preauth_info, and on a deassemble_neg_contexts() failure kfrees it and sets it to NULL. Both the allocation and the free/NULL happen under ksmbd_conn_lock(conn) (the connection srv_mutex), which is held across the whole handler body. The response send path smb3_preauth_hash_rsp(), called from the send: block of __handle_ksmbd_work(), reads conn->preauth_info and dereferences conn->preauth_info->Preauth_HashValue (via ksmbd_gen_preauth_integrity_hash()) without taking conn_lock. When a client drives two SMB2 NEGOTIATE requests on the same connection, one worker can free conn->preauth_info on the failing-negotiate path while a concurrent send-path worker is reading it, producing a slab use-after-free read (KASAN-confirmed). The send-path read tested conn->preauth_info for NULL but raced with the free that occurs between the NULL check and the dereference, so the NULL guard alone does not close the window. Serialize the NEGOTIATE-branch read in smb3_preauth_hash_rsp() under ksmbd_conn_lock(conn) and re-check conn->preauth_info inside the lock. Because the negotiate handler holds conn_lock across its kfree + NULL assignment, a reader that also takes conn_lock either runs fully before the allocation or fully after the NULL store, and can never observe the freed-but-not-yet-NULLed pointer. ksmbd_gen_preauth_integrity_hash() takes no locks itself (it only computes a SHA-512 over the buffer), so no lock-ordering inversion is introduced, and conn_lock is a sleepable mutex which is safe on this send path (it already performs network I/O).
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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，该漏洞源于并发SMB2 NEGOTIATE请求时对conn->preauth_info的释放后重用，可能导致释放后重用攻击。
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 dd4e4c811898410e6a3ae3b63207b7c542860907 ~ c7bef84740d1d57848c74f6f5b996606e43ea4fe -
Linux Linux 6.0 -

II. Public POCs for CVE-2026-72422

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III. Intelligence Information for CVE-2026-72422

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Patches & Fixes for CVE-2026-72422 (7)

Same Patch Batch · Linux · 2026-08-15 · 844 CVEs total

CVE-2026-74279 10.0 CRITICAL crypto: cavium/cpt - fix DMA cleanup using wrong loop index
CVE-2026-74280 10.0 CRITICAL crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
CVE-2026-72421 10.0 CRITICAL ipv4: fib: Don't ignore error route in local/main tables.
CVE-2026-74475 10.0 CRITICAL vxlan: use neigh_ha_snapshot() in route_shortcircuit()
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-2026-74309 10.0 CRITICAL vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
CVE-2026-72493 9.9 CRITICAL net: serialize netif_running() check in enqueue_to_backlog()
CVE-2026-72084 9.8 CRITICAL scsi: target: Bound PR-OUT TransportID parsing to the received buffer
CVE-2026-74480 9.8 CRITICAL net: bridge: stop fast-leave after deleting a port group
CVE-2026-72083 9.8 CRITICAL scsi: target: core: Fix iSCSI ISID use-after-free in REGISTER AND MOVE
CVE-2026-74345 9.8 CRITICAL RDMA/siw: Fix endpoint/socket association handling
CVE-2026-72248 9.8 CRITICAL netfilter: flowtable: support IPIP tunnel with direct xmit
CVE-2026-72249 9.8 CRITICAL netfilter: flowtable: use dst in this direction when pushing IPIP header
CVE-2026-74493 9.8 CRITICAL net/smc: fix socket use-after-free during link group termination
CVE-2026-74495 9.8 CRITICAL igbvf: Fix leak in TX DMA error cleanup
CVE-2026-72251 9.8 CRITICAL netfilter: nf_nat_sip: reload possible stale data pointer
CVE-2026-74398 9.8 CRITICAL ipv6: addrconf: bail out of dad_failure when state is no longer POSTDAD
CVE-2026-74401 9.8 CRITICAL dlm: fix add msg handle in send_queue ordered
CVE-2026-72317 9.8 CRITICAL SUNRPC: pin upper rpc_clnt across the TLS connect_worker

Showing top 20 of 844 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-72422

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