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CVE-2026-53612— util-linux mount hook_owner TOCTOU allows local privilege escalation

Quick assessment

Affected
util-linux util-linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

util-linux 是 Linux 系统工具的一个集合。在 util-linux 2.39 至 2.41.4 版本以及 2.42 至 2.42.1 版本中，具有 SUID 权限的 实用程序的后挂载钩子函数（位于 ）会对已验证的挂载目标执行基于路径的 和 操作。本地低权限用户若通过 配置文件中的 或 选项，并配合 、 或 选项获得授权，可利用 系统调用与挂载目标的可写祖先目录之间形成竞态条件（race condition），从而将本应应用于挂载目标的特权所有权或权限更改重定向到由 root 用户拥有的路径上，可能导

CVSS 7.0 · High

Affected Version Matrix 2

VendorProduct Version RangeStatus
util-linux util-linux >= 2.39, < 2.41.5 affected
>= 2.42, < 2.42.2 affected
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I. Basic Information for CVE-2026-53612

Vulnerability Information
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Vulnerability Title
util-linux mount hook_owner TOCTOU allows local privilege escalation
Source: CVE Program / CVE List V5
Vulnerability Description
util-linux is a random collection of Linux utilities. In util-linux 2.39 through 2.41.4 and 2.42 through 2.42.1, the SUID `mount` utility's `hook_owner.c` post-mount hook performs path-based `chmod()` and `lchown()` operations on a previously validated mount target. A local low-privileged user authorized by an `/etc/fstab` entry with `user` or `users` and an `X-mount.mode`, `X-mount.owner`, or `X-mount.group` option can use `renameat2(RENAME_EXCHANGE)` to race a writable ancestor of the target and redirect the privileged ownership or mode change to a root-owned path, potentially gaining root privileges. This issue is fixed in 2.41.5 and 2.42.2.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
util-linux util-linux >= 2.39, < 2.41.5 -

II. Public POCs for CVE-2026-53612

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III. Intelligence Information for CVE-2026-53612

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Patches & Fixes for CVE-2026-53612 (4)

Other References for CVE-2026-53612 (3)

Same Patch Batch · util-linux · 2026-10-14 · 4 CVEs total

CVE-2026-53615 8.0 HIGH util-linux libblkid DOS extended-partition overflow produces invalid partition metadata
CVE-2026-53613 7.0 HIGH util-linux mount target TOCTOU allows local privilege escalation
CVE-2026-53614 7.0 HIGH util-linux LIBMOUNT_FORCE_MOUNT2 allows nosuid and noexec bypass

IV. Related Vulnerabilities

Same product: util-linux
Same vendor: util-linux
Same weakness: CWE-367

V. Comments for CVE-2026-53612

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