NULL pointer dereference in Linux kernel - CVE-2026-53271

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Main Vulnerability Database Vulnerabilities #VU135475

NULL pointer dereference in Linux kernel - CVE-2026-53271

Published: June 26, 2026


Vulnerability identifier: #VU135475
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-53271
CWE-ID: CWE-476
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to a null pointer dereference in smb2_oplock_break_noti() and smb2_lease_break_noti() in fs/smb/server/oplock.c when handling oplock or lease break notifications during a concurrent SMB2 LOGOFF. A remote attacker can trigger a concurrent logoff condition to cause a denial of service.

The issue is remotely triggerable and results in a kernel oops when ksmbd_conn_r_count_inc(conn) dereferences a NULL connection pointer.


Affected software

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)

How to mitigate CVE-2026-53271

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-31.31~24.04.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12, 7.0.0-1012.12~24.04.1
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13

External References

Related Security Bulletins