ksmbd: fix null pointer dereference in proc_show_files() (CVE-2026-64140) | HOL Guard CVE

High · CVSS 7.5CVE-2026-64140

ksmbd: fix null pointer dereference in proc_show_files()

Answer in brief

CVE-2026-64140 records a High severity (CVSS 7.5) vulnerability in ksmbd: fix null pointer dereference in proc_show_files(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jul 19, 2026Updated Aug 18, 2026Source checked Sep 20, 2026First seen by HOL Aug 5, 2026Material review Aug 18, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 7 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:o:linux:linux_kernel::::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc1::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc2::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc3::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc4::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=b38f99c1217ae04753340f0fdcd8f35bf56841dc <8eab081627b67216d1c8f638b68289b500dc9a6b \|\| >=b38f99c1217ae04753340f0fdcd8f35bf56841dc <904901561e61a2b559070b20c74a8c95491f30aa	8eab081627b67216d1c8f638b68289b500dc9a6b, 904901561e61a2b559070b20c74a8c95491f30aa
Linux/Linuxgeneric	7.0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 8eab081627b67216d1c8f638b68289b500dc9a6b if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 18, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 5, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.