{"id":"CVE-2026-98990","revision":"afea7fc3c9b64764b6478bd2cabc80ff","records":[{"revision":"afea7fc3c9b64764b6478bd2cabc80ff","observedAt":"2026-10-23T16:01:20.601+00:00","statement":{"source":"cve-program","id":"CVE-2026-98990","aliases":[],"title":"namespace: check a submount for references right before unmounting it","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: check a submount for references right before unmounting it\n\nshrink_submounts() and mark_mounts_for_expiry() first collect all the\nmounts they are allowed to unmount and then unmount them.\n\nWhether a mount is busy is decided by propagate_mount_busy() on the\ntree. But unmounting the first mount changes the tree that the second\none propagates into. propagate_umount()\nmoves a surviving overmount off a copy it unmounts and mounts it where\nthe copy was mounted. If that's where the propagated copy of the second\nvictim is looked up the overmount becomes a candidate of the second\numount_tree(). It's childless and so trim_one() commits it without\nlooking at its reference count.\n\nSo a synchronous umount pulls out a busy mount that is in use somewhere\nelse and marks it MNT_SYNC_UMOUNT while it has users:\n\n  umount2(/tmp/plshrink/p1, 0) = 0 errno 0\n  cwd is (unreachable)\n\nThe same two umounts requested one after the other fail with EBUSY.\nThis needs a mount with MNT_SHRINKABLE, i.e., automounted submounts of\nNFS, AFS and CIFS or the tracefs mount below debugfs. Bind mounts\ninherit the flag.\n\nCheck each mount right before it is unmounted under the same hold of\nnamespace_sem and mount_lock as the umount itself. Make sure that the\nalgorithm stays linear.","state":0,"publishedAt":"2026-10-23T12:20:09.349+00:00","modifiedAt":"2026-10-23T12:20:09.349+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/namespace.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"1064f874abc0d05eeed8993815f584d847b72486\",\n                            \"lessThan\": \"f6394281834492c6516a405a348b545ae698a331\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1064f874abc0d05eeed8993815f584d847b72486\",\n                            \"lessThan\": \"6e4012e571867868b545c91ca9d6095fdb709907\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1064f874abc0d05eeed8993815f584d847b72486\",\n                            \"lessThan\": \"d73f04e92c1aab78d96ac6cadb234c8a3a373d22\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1064f874abc0d05eeed8993815f584d847b72486\",\n                            \"lessThan\": \"18902a23ef36f83d32bafc58ae2484e6bb4bb8ef\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"1064f874abc0d05eeed8993815f584d847b72486\",\n                            \"lessThan\": \"32bf92416614a1e3ff3524fc6b780259c7aad3ef\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"5e6ef5ef6eaf690faad3a7c6c665ebf45d7b6ccf\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"839d42687dfce0ed0ea2c6bd8d707cc0e276fbe7\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"808e83e5add13152bd4a88346487de68395c136b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"6de9d08a9718ee9c12ba6343c50141c2d633e3dc\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"4.1.40\",\n                            \"lessThan\": \"4.2\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"4.4.54\",\n                            \"lessThan\": \"4.5\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"4.9.15\",\n                            \"lessThan\": \"4.10\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"4.10.3\",\n                            \"lessThan\": \"4.11\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\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/namespace.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.11\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.11\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.160\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.113\",\n                            \"lessThanOrEqual\": \"6.12.*\",\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":[],"references":["https://git.kernel.org/stable/c/f6394281834492c6516a405a348b545ae698a331","https://git.kernel.org/stable/c/6e4012e571867868b545c91ca9d6095fdb709907","https://git.kernel.org/stable/c/d73f04e92c1aab78d96ac6cadb234c8a3a373d22","https://git.kernel.org/stable/c/18902a23ef36f83d32bafc58ae2484e6bb4bb8ef","https://git.kernel.org/stable/c/32bf92416614a1e3ff3524fc6b780259c7aad3ef"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98990","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98990","identifiers":["CVE-2026-98990"]},"retained":false,"historicalAffected":[]}],"coverage":[]}