CVE-2026-27456 in util-linux
要約 (英語)
util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the SUID binary /usr/bin/mount from util-linux. The mount binary, when setting up loop devices, validates the source file path with user privileges via fork() + setuid() + realpath(), but subsequently re-canonicalizes and opens it with root privileges (euid=0) without verifying that the path has not been replaced between both operations. Neither O_NOFOLLOW, nor inode comparison, nor post-open fstat() are employed. This allows a local unprivileged user to replace the source file with a symlink pointing to any root-owned file or device during the race window, causing the SUID binary to open and mount it as root. Exploitation requires an /etc/fstab entry with user,loop options whose path points to a directory where the attacker has write permission, and that /usr/bin/mount has the SUID bit set (the default configuration on virtually all Linux distributions). The impact is unauthorized read access to root-protected files and block devices, including backup images, disk volumes, and any file containing a valid filesystem. This issue has been patched in version 2.41.4.
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責任者
GitHub_M
予約する
2026年02月19日
公開
2026年04月04日
ステータス
確認済み
エントリ
VulDB provides additional information and datapoints for this CVE:
| 識別子 | 脆弱性 | CWE | 悪用可 | 対策 | CVE |
|---|---|---|---|---|---|
| 355220 | util-linux mount fork 特権昇格 | 59 | 未定義 | 公式な修正 | CVE-2026-27456 |