SB20260816493 - NULL pointer dereference in Linux kernel fs

Description

This security bulletin contains information about 1 vulnerability.

1) NULL pointer dereference (CVE-ID: CVE-2026-72034)

CWE-ID: CWE-476 - NULL Pointer Dereference

CVSSv4: 5.6 [CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local privileged user to cause a denial of service.

The vulnerability exists due to a null pointer dereference in capable_wrt_mount() when handling open_by_handle_at() on a detached mount during a race condition. A local privileged user can trigger the race using open_tree(..., OPEN_TREE_CLONE) and open_by_handle_at() to cause a denial of service.

The issue occurs when a detached mount is dissolved while open_by_handle_at() is between mount state checks, causing mount->mnt_ns to become NULL.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/15104234c267ebe04b9f9a73e5c2179cc265ff60
• https://git.kernel.org/stable/c/6c52226072a3c61337b1eec1799bb987748884fa
• https://git.kernel.org/stable/c/6c732471740bc2ac9b0946134f9f551dc75f4369
• https://git.kernel.org/stable/c/6ee183d89261bf1d1cf9f06d80a40dab8f36ee55