CVE Catalog

CVE-2026-64140

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.36%

29th percentile - higher than 29% of all known CVEs

Summary

In the Linux kernel ksmbd filesystem, a null pointer dereference vulnerability was found in proc_show_files(). When an SMB2 client opens a file with a durable v2 handle and then issues SMB2 SESSION_LOGOFF, the fp->tcon pointer is cleared but the entry remains in global_ft.idr. Reading /proc/fs/ksmbd/files during this window causes a kernel panic.

Risk Assessment

An attacker with SMB2 access can trigger a kernel panic (denial of service) by opening a file with a durable handle, logging off the session, and reading the /proc/fs/ksmbd/files file. This vulnerability can disrupt the ksmbd service and the entire system.

Recommendation

Immediately update the Linux kernel to a version containing the fix (commit 70390501d194 or later). If an update is not possible, temporarily restrict access to /proc/fs/ksmbd/files (e.g., set permissions to 0000) or disable durable handles in the SMB configuration.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

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.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS