{"id":"CVE-2026-98991","revision":"188dbb443dda49a899e9a80cc0e1091a","records":[{"revision":"188dbb443dda49a899e9a80cc0e1091a","observedAt":"2026-10-24T16:17:04.479+00:00","statement":{"source":"cve-program","id":"CVE-2026-98991","aliases":[],"title":"namespace: queue a mount only once for mount notifications","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: queue a mount only once for mount notifications\n\nmnt_notify_add() puts a mount on notify_list. It doesn't check whether\nthe mount is on the list already. That's fine as long as every mount is\nqueued at most once per namespace_sem hold. It isn't.\n\npropagate_umount() moves a surviving overmount off a stack of mounts\nthat are going away and queues it as moved. shrink_submounts() and\nmark_mounts_for_expiry() call umount_tree() for several mounts under a\nsingle namespace_sem hold. So the second umount_tree() can take down\nexactly the mount the first one reparented, reparent it once more and so\nend up queueing it a second time.\n\nThe second list_add_tail() cuts the mounts queued in between out of the\nlist while the head still points at the last of them. notify_mnt_list()\nthen only visits that one mount and the others are freed after the grace\nperiod with notify_list still pointing at them. Every later mount\noperation on the host walks freed memory:\n\n  BUG: KASAN: slab-use-after-free in __list_add_valid_or_report\n  Read of size 8 at addr ffff8881003d57e0 by task notify_dq/162\n   __list_add_valid_or_report+0x15c/0x1a0\n   mnt_add_to_ns+0x322/0x890\n   attach_recursive_mnt.isra.0+0xf2a/0x1a00\n   path_mount+0x139c/0x1d40\n\nThis needs a mount with MNT_SHRINKABLE to bind from. That's what\nfinish_automount() creates (submounts of NFS, AFS and CIFS and the\ntracefs mount below debugfs). Bind mounts inherit the flag. A mount\nnamespace with a FAN_MARK_MNTNS mark does the rest and root in a user\nnamespace can have both.\n\nInitialize to_notify in alloc_vfsmnt() and leave a mount alone that is\nqueued already. mnt_notify() looks at the state the mount has when the\nlist is drained so a single entry per mount is enough. The move event\nfor a mount that is unmounted under the same hold is lost. That's fine.\nThe detach is what matters.","state":0,"publishedAt":"2026-10-23T12:20:10.289+00:00","modifiedAt":"2026-10-24T14:09:52.901+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/mount.h\",\n                        \"fs/namespace.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"bf630c40164162ba1d3933c2f5e3397d083e0948\",\n                            \"lessThan\": \"acbe9e4418e2ef7bef1a12e62e0e7d6145a15190\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"bf630c40164162ba1d3933c2f5e3397d083e0948\",\n                            \"lessThan\": \"702ff3fe499876e09c45558a05366d21a5bc41ab\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"bf630c40164162ba1d3933c2f5e3397d083e0948\",\n                            \"lessThan\": \"bd2feb7796b6585938a4241e7b7c4148a6f7b762\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"fs/mount.h\",\n                        \"fs/namespace.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.15\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.15\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.57\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.11\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/acbe9e4418e2ef7bef1a12e62e0e7d6145a15190","https://git.kernel.org/stable/c/702ff3fe499876e09c45558a05366d21a5bc41ab","https://git.kernel.org/stable/c/bd2feb7796b6585938a4241e7b7c4148a6f7b762"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98991","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98991","identifiers":["CVE-2026-98991"]},"retained":false,"historicalAffected":[]}],"coverage":[]}