CVE-2026-74259

Received Received - Intake

Kernel NULL Pointer Dereference in Linux Kernel CIFS

Publication date: 2026-08-15

Last updated on: 2026-08-17

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: remove all cifs files before kill super Cifs files may be put into fileinfo_put_wq during umounting cifs. After umount done, cifsFileInfo_put_final is called, which cause following BUG: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... [ 134.222152] list_lru_add+0x64/0x1a0 [ 134.222399] ? cifs_put_tcon+0x171/0x340 [cifs] [ 134.222772] d_lru_add+0x44/0x60 [ 134.222997] dput+0x1fc/0x210 [ 134.223213] cifsFileInfo_put_final+0x11a/0x140 [cifs] [ 134.223576] process_one_work+0x17c/0x320 [ 134.223843] worker_thread+0x188/0x280 [ 134.224084] ? __pfx_worker_thread+0x10/0x10 [ 134.224366] kthread+0xcc/0x100 [ 134.224576] ? __pfx_kthread+0x10/0x10 [ 134.224827] ret_from_fork+0x30/0x50 [ 134.225063] ? __pfx_kthread+0x10/0x10 [ 134.225328] ret_from_fork_asm+0x1b/0x30 This can be reproduce by following: unshare -n bash -c " mkdir -p ${CIFS_MNT} ip netns attach root 1 ip link add eth0 type veth peer veth0 netns root ip link set eth0 up ip -n root link set veth0 up ip addr add 192.168.0.2/24 dev eth0 ip -n root addr add 192.168.0.1/24 dev veth0 ip route add default via 192.168.0.1 dev eth0 ip netns exec root sysctl net.ipv4.ip_forward=1 ip netns exec root iptables -t nat -A POSTROUTING -s 192.168.0.2 -o ${DEV} -j MASQUERADE mount -t cifs ${CIFS_PATH} ${CIFS_MNT} -o vers=3.0,sec=ntlmssp,credentials=${CIFS_CRED},rsize=65536,wsize=65536,cache=none,echo_interval=1 touch ${CIFS_MNT}/a.txt ip netns exec root iptables -t nat -D POSTROUTING -s 192.168.0.2 -o ${DEV} -j MASQUERADE " umount ${CIFS_MNT}

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-15

Last Modified

2026-08-17

Generated

2026-09-04

AI Q&A

2026-08-15

EPSS Evaluated

2026-09-03

NVD

CVE-2026-74259

EUVD

EUVD-2026-59406

Affected Vendors & Products

Currently, no data is known.

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability in the Linux kernel involves a NULL pointer dereference in the CIFS (Common Internet File System) module. It occurs during unmounting of a CIFS filesystem when files are still referenced in a work queue. The bug leads to a kernel crash due to accessing invalid memory at address 0000000000000000.

Detection Guidance

This vulnerability is related to the Linux kernel's CIFS (Common Internet File System) module and may cause a kernel NULL pointer dereference during CIFS unmount operations. Detection typically involves checking kernel logs for NULL pointer dereference errors or crashes during CIFS operations.

Impact Analysis

This vulnerability can cause system instability or crashes when unmounting CIFS filesystems, potentially leading to denial of service. Users relying on CIFS for network file sharing may experience unexpected system failures during routine operations.

Compliance Impact

This vulnerability causes a kernel NULL pointer dereference during CIFS unmounting, leading to system instability or crashes. It does not directly affect data confidentiality, integrity, or availability in a way that would violate GDPR or HIPAA compliance requirements.

Mitigation Strategies

Apply the latest kernel updates or patches that address this specific CIFS issue. Avoid unmounting CIFS shares abruptly and ensure proper cleanup of CIFS files before unmounting. Monitor kernel logs for related errors.

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