What is the CVSS score of CVE-2026-64140?

CVE-2026-64140 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.2%.

Which versions of Linux Kernel ksmbd are affected by CVE-2026-64140?

CVE-2026-64140 is a denial-of-service vulnerability in Linux's in-kernel SMB server (ksmbd) that can cause kernel panics on file servers configured with durable handles enabled.. A patch is available.

How to fix or mitigate CVE-2026-64140?

Within 24 hours, identify all Linux systems running ksmbd with durable handles enabled and classify them by criticality to file-sharing operations. Within 7 days, apply the available vendor patch to affected systems in a non-production test environment first, then deploy to production systems beginning with less critical file servers. Within 30 days, ensure patch deployment is complete across all affected systems and validate that kernel stability has been restored through monitoring of system logs and crash reports.

Linux Kernel ksmbd CVE-2026-64140

EUVD-2026-45825 HIGH

NULL Pointer Dereference (CWE-476)

2026-07-19 Linux

GHSA-3wf5-rcm5-gfqq

Denial Of Service Linux Null Pointer Dereference Canonical

7.5

CVSS 3.1 · Vendor: Linux

Severity by source

Vendor (Linux) PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

vuln.today AI

4.4 MEDIUM

Crash fires only when root reads /proc/fs/ksmbd/files (mode 0400), so AV:L and PR:H; DoS-only means C:N/I:N/A:H; seconds-long window keeps AC:L.

3.1 AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H

4.0 AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SUSE

HIGH

qualitative

Primary rating from Vendor (Linux).

CVSS VectorVendor: Linux

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

Jul 20, 2026 - 17:41 vuln.today

CVSS changed

Jul 20, 2026 - 15:22 NVD

7.5 (HIGH)

Patch available

Jul 19, 2026 - 17:03 EUVD

CVE Published

Jul 19, 2026 - 15:40 cve.org

UNKNOWN (no severity yet)

CVE Published

Jul 19, 2026 - 15:40 cve.org

HIGH 7.5

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: fix null pointer dereference in proc_show_files()

When a SMB2 client opens a file with a durable v2 handle and then issues SMB2 SESSION_LOGOFF, session_fd_check() clears fp->tcon = NULL on the reconnectable file pointer but leaves the fp registered in global_ft.idr until the durable scavenger fires (up to fp->durable_timeout seconds later).

During that window any read of /proc/fs/ksmbd/files (mode 0400) panics the kernel because proc_show_files() walks global_ft.idr and unconditionally dereferences fp->tcon->id with no NULL guard.

Reproducer requires only a successful SMB2 SESSION_SETUP and a share configured with 'durable handles = yes'. KASAN report on mainline 70390501d194:

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:proc_show_files+0x118/0x740 Call Trace: proc_show_files+0x118/0x740 seq_read_iter+0x4ef/0xe10 proc_reg_read_iter+0x1b7/0x280 ...

Guard the dereference. A durable-disconnected fp legitimately has no tcon; report its tree id as 0 rather than oopsing.

AnalysisAI

Kernel-panic denial of service in the Linux kernel's in-kernel SMB server (ksmbd) allows the file-pointer table to retain a durable-handle file object with a NULL tcon after a client issues SMB2 SESSION_LOGOFF; any subsequent read of /proc/fs/ksmbd/files then dereferences the NULL fp->tcon in proc_show_files() and crashes the host. Affected are kernels running ksmbd on shares configured with 'durable handles = yes'. There is no public exploit identified at time of analysis and EPSS is low (0.16%, 6th percentile), consistent with a stability/robustness bug rather than a weaponizable RCE.

Technical ContextAI

The flaw is in ksmbd, the Linux kernel's native SMB3 file-server module (CPE cpe:2.3:a:linux:linux). ksmbd tracks open files in a global IDR (global_ft.idr). When a durable v2 handle is left reconnectable and the client sends SMB2 SESSION_LOGOFF, session_fd_check() sets fp->tcon = NULL but intentionally leaves the file pointer registered so the client can reconnect, until the durable scavenger reclaims it after fp->durable_timeout seconds. The debug interface /proc/fs/ksmbd/files (mode 0400) enumerates that IDR and unconditionally dereferences fp->tcon->id. Because a durable-disconnected fp legitimately has a NULL tcon, this is a classic NULL pointer dereference (CWE-476); KASAN reports it as a null-ptr-deref / general protection fault at proc_show_files+0x118 on mainline 70390501d194. The fix adds a NULL guard, reporting tree id 0 instead of oopsing.

RemediationAI

Vendor-released patch: update to a Linux kernel including the ksmbd fix (stable commits 8eab081627b67216d1c8f638b68289b500dc9a6b and 904901561e61a2b559070b20c74a8c95491f30aa; distribution builds corresponding to 7.0.11 / 7.1 per EUVD-2026-45825). Apply your distribution's kernel update and reboot. If patching must be deferred, the most effective compensating control is to disable durable handles on ksmbd shares (set 'durable handles = no' in the share config), which removes the reconnectable-fp window at the cost of losing durable-handle resilience for clients. Alternatively, restrict or avoid reads of /proc/fs/ksmbd/files (already root-only at mode 0400) - ensure monitoring/automation does not poll this debug file while durable handles are in use - or unload the ksmbd module entirely if the in-kernel SMB server is not required, which stops all SMB serving via ksmbd. See https://git.kernel.org/stable/c/8eab081627b67216d1c8f638b68289b500dc9a6b for the patch.

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Vendor StatusVendor

SUSE

Severity: Important

Product	Status
SUSE Linux Enterprise Desktop 15 SP7	Affected
SUSE Linux Enterprise Desktop 15 SP7	Affected
SUSE Linux Enterprise High Availability Extension 15 SP7	Affected
SUSE Linux Enterprise High Availability Extension 15 SP7	Affected
SUSE Linux Enterprise High Availability Extension 16.0	Affected

CVE-2026-64140 vulnerability details – vuln.today

Back

Linux Kernel ksmbd CVE-2026-64140

Severity by source

CVSS VectorVendor: Linux

Lifecycle Timeline

DescriptionCVE.org

AnalysisAI

Technical ContextAI

RemediationAI

More in Canonical

Same weakness CWE-476 – NULL Pointer Dereference

Same technique Denial Of Service

Vendor StatusVendor

SUSE

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External POC / Exploit Code