{"id":"CVE-2026-98995","title":"namespace: reset the old parent's ->overmount in mnt_change_mountpoint()","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: reset the old parent's ->overmount in mnt_change_mountpoint()\n\n__umount_mnt() resets ->overmount of the parent when it unmounts the\nmount that overmounts it.…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= ffdc52fbbd5835a936ad683c943d6d103a2d4514 < 5e0a1f2c753a79749bc2ead3ae2f2ede3941daa5","Linux >= ffdc52fbbd5835a936ad683c943d6d103a2d4514 < 08d575ee89393fd812dbdca7b5d7b4574cd5a564","Linux >= ffdc52fbbd5835a936ad683c943d6d103a2d4514 < 476ef286a7a5db8bda51325dc0c45887b4d99d9a","Linux 6.17"],"published":"2026-10-23","updated":"2026-10-23","sourceUpdated":"2026-10-23T12:20:14.155Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98995","references":[{"url":"https://git.kernel.org/stable/c/5e0a1f2c753a79749bc2ead3ae2f2ede3941daa5"},{"url":"https://git.kernel.org/stable/c/08d575ee89393fd812dbdca7b5d7b4574cd5a564"},{"url":"https://git.kernel.org/stable/c/476ef286a7a5db8bda51325dc0c45887b4d99d9a"}],"tags":["cve.org"],"ingestedAt":"2026-10-23T13:24:55.544Z","slug":"CVE-2026-98995","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: reset the old parent's ->overmount in mnt_change_mountpoint()\n\n__umount_mnt() resets ->overmount of the parent when it unmounts the\nmount that overmounts it. mnt_change_mountpoint() doesn't. It moves the\nmount to its new parent and leaves the old one pointing at it.\n\nFor a mount that is moved beneath in attach_recursive_mnt() that doesn't\nmatter. The new mount has already reset ->overmount of the old parent by\nthe time the old top mount is moved onto it.\n\nIt matters for reparent() though. propagate_umount() moves a surviving\novermount onto the first ancestor that isn't going to be unmounted. The\nmount it was taken from is unmounted immediately afterwards. If a file\ndescriptor keeps that unmounted mount alive ->overmount points at the\nmoved mount. That's a dangling pointer and UAF as the moved mount is\nunmounted and freed.\n\ndo_lock_mount() follows ->overmount from the target path under\nmount_lock. With a file descriptor on such a mount as the target of a\nmount beneath topmost_overmount() walks into the freed mount and\ndo_lock_mount() takes references on whatever it finds there.\n\nSo reset ->overmount of the old parent in mnt_change_mountpoint() the\nsame way __umount_mnt() does. A mount's ->overmount is then always a\nmount that is attached to it.\n\n## Affected\n\n- `Linux >= ffdc52fbbd5835a936ad683c943d6d103a2d4514 < 5e0a1f2c753a79749bc2ead3ae2f2ede3941daa5`\n- `Linux >= ffdc52fbbd5835a936ad683c943d6d103a2d4514 < 08d575ee89393fd812dbdca7b5d7b4574cd5a564`\n- `Linux >= ffdc52fbbd5835a936ad683c943d6d103a2d4514 < 476ef286a7a5db8bda51325dc0c45887b4d99d9a`\n- `Linux 6.17`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}