{"id":"AZL-81846","summary":"CVE-2026-27456 affecting package util-linux for versions less than 2.40.2-4","details":"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.","modified":"2026-08-31T05:26:27Z","published":"2026-04-03T22:16:25Z","upstream":["CVE-2026-27456"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27456"}],"affected":[{"package":{"name":"util-linux","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/util-linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.40.2-4"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-81846.json"}}],"schema_version":"1.9.0"}