{"id":"CVE-2026-98989","revision":"3feb051f8acf49ee926fc142a6cc29ce","records":[{"revision":"3feb051f8acf49ee926fc142a6cc29ce","observedAt":"2026-10-23T16:01:20.601+00:00","statement":{"source":"cve-program","id":"CVE-2026-98989","aliases":[],"title":"namespace: check a recursive bind mount for mount namespace loops","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnamespace: check a recursive bind mount for mount namespace loops\n\ndo_loopback() refuses to bind mount the file of a mount namespace that\nis as old as the caller's or older because a mount namespace that holds\na mount of its own file, or of an ancestor's, would cause a cycle. But\nit only checks the dentry the bind mount starts from. With MS_REC\neverything below it is copied and do_loopback() passes\nCL_COPY_MNT_NS_FILE so mount namespace files below the source are\ncopied.\n\nThat's fine for a source in the caller's own mount namespace. Every\nmount namespace file in there passed the same check when it was\nbind-mounted. It isn't fine for a source in another mount namespace.\nmay_copy_tree() accepts a bind mount of any nsfs or pidfs file no matter\nwhat mount namespace it lives in so that /proc/<pid>/ns/<ns> and pidfds\ncan be bind mounted. If we create a bind-mount stack of mount namespaces\nfile descriptors the kernel will copy them irrespective of their\nancestoral relationship to the mount namespace in question:\n\n  151 146 0:7 net:[4026531833] /tmp/nrc/y rw - nsfs nsfs rw\n  152 151 0:7 mnt:[4026532293] /tmp/nrc/y rw - nsfs nsfs rw\n\nMount 152 is a mount of the mount namespace file of mount namespace\n4026532293 inside mount namespace 4026532293. That namespace and every\nmount in it are leaked... All it takes is a process in an older mount\nnamespace that stacks the file and repeating it leaks without limit:\n\n  after control: Shmem:               380 kB\n  child: mount(/proc/self/fd/6, MS_BIND|MS_REC): ok\n  after cycle: Shmem:             65916 kB\n\ndo_move_mount() runs check_for_nsfs_mounts() over a detached tree for\nexactly that reason. Do the same for the copy before it is grafted.","state":0,"publishedAt":"2026-10-23T12:20:08.366+00:00","modifiedAt":"2026-10-23T12:20:08.366+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\": \"e149ed2b805fefdccf7ccdfc19eca22fdd4514ac\",\n                            \"lessThan\": \"a0ba48256f5dff6f75a45f8ce39fe57f21df1022\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e149ed2b805fefdccf7ccdfc19eca22fdd4514ac\",\n                            \"lessThan\": \"37a82f400efa4d263542a5fa41755b21057f1e5d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"e149ed2b805fefdccf7ccdfc19eca22fdd4514ac\",\n                            \"lessThan\": \"c640a01a78e42302879006ed7b7d5a9a943ba815\",\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/namespace.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"3.19\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"3.19\",\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/a0ba48256f5dff6f75a45f8ce39fe57f21df1022","https://git.kernel.org/stable/c/37a82f400efa4d263542a5fa41755b21057f1e5d","https://git.kernel.org/stable/c/c640a01a78e42302879006ed7b7d5a9a943ba815"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98989","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98989","identifiers":["CVE-2026-98989"]},"retained":false,"historicalAffected":[]}],"coverage":[]}