CVE-2026-63810
Received Received - Intake

Kernel NULL Pointer Dereference in Linux Kernel

Publication date: 2026-07-19

Last updated on: 2026-07-19

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: block: Avoid mounting the bdev pseudo-filesystem in userspace The bdev pseudo-filesystem is an internal kernel filesystem with which userspace should not interfere. Unregister it so that userspace cannot even attempt to mount it. This fixes a bug [1] that occurs when attempting to access files, because the system call move_mount() uses pointers declared in the inode_operations structure, which for the bdev pseudo-filesystem are always equal to 0. `inode->i_op = &empty_iops;` [1] BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 23380067 P4D 23380067 PUD 23381067 PMD 0 Oops: 0010 [#1] PREEMPT SMP KASAN NOPTI CPU: 2 PID: 17125 Comm: syz-executor.0 Not tainted 6.1.155-syzkaller-00350-g84221fde2681 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:0x0 Call Trace: <TASK> lookup_open.isra.0+0x700/0x1180 fs/namei.c:3460 open_last_lookups fs/namei.c:3550 [inline] path_openat+0x953/0x2700 fs/namei.c:3780 do_filp_open+0x1c5/0x410 fs/namei.c:3810 do_sys_openat2+0x171/0x4d0 fs/open.c:1318 do_sys_open fs/open.c:1334 [inline] __do_sys_openat fs/open.c:1350 [inline] __se_sys_openat fs/open.c:1345 [inline] __x64_sys_openat+0x13c/0x1f0 fs/open.c:1345 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-07-19
Last Modified
2026-07-19
Generated
2026-07-20
AI Q&A
2026-07-19
EPSS Evaluated
N/A
NVD
CVE-2026-63810
EUVD
EUVD-2026-45476

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel 6.1.155

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-UNKNOWN

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability in the Linux kernel involves the bdev pseudo-filesystem, an internal kernel component that userspace should not access. The kernel unregisters this filesystem to prevent userspace from mounting it. A bug occurs when attempting to access files via the move_mount() system call, as the inode operations for the bdev filesystem are set to zero, leading to a NULL pointer dereference and kernel crash.

Detection Guidance

This vulnerability is specific to the Linux kernel and does not have a direct network-based detection method. To check if your system is affected, verify the kernel version and whether the bdev pseudo-filesystem is unregistered. Use commands like 'uname -a' to check the kernel version and 'mount | grep bdev' to see if the bdev filesystem is mounted.

Impact Analysis

This vulnerability can cause a kernel crash (oops) when userspace attempts to interact with the bdev pseudo-filesystem. This may lead to denial-of-service conditions, system instability, or potential privilege escalation if exploited maliciously.

Compliance Impact

This vulnerability does not directly affect compliance with GDPR, HIPAA, or similar standards. It is a kernel-level issue involving a NULL pointer dereference in the bdev pseudo-filesystem, which could lead to system crashes but does not involve data exposure or unauthorized access that would typically impact regulatory compliance.

Mitigation Strategies

Update your Linux kernel to the latest stable version that includes the fix for this vulnerability. If you cannot update immediately, ensure the bdev pseudo-filesystem is not mounted by checking with 'mount | grep bdev' and unmounting if necessary. Monitor kernel logs for NULL pointer dereference errors.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-63810. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart