SB20261023171 - Use-after-free in Linux kernel clone_mnt() and mount namespace lifecycle handling in fs/namespace.c

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Main Vulnerability Database SB20261023171

SB20261023171 - Use-after-free in Linux kernel clone_mnt() and mount namespace lifecycle handling in fs/namespace.c

Published: October 23, 2026

Security Bulletin ID SB20261023171
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Local access
Highest impact Denial of service

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Use-after-free (CVE-ID: CVE-2026-98993)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 6.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a local user to cause a denial of service and potentially corrupt kernel memory through a use-after-free.

The vulnerability exists due to improper inheritance of the MNT_UMOUNT flag in clone_mnt() when copying a lazily unmounted mount kept alive by an open file descriptor. A local user can perform bind-mount and namespace operations on the resulting mount to disrupt mount tracking, cause nonterminating mount traversal, or trigger access to a freed mount namespace structure.

The detached source mount can be copied through this path only when its root is an nsfs or pidfs file.


Remediation

Install update from vendor's website.

References