{"schema":"threatline.record/2","record":{"id":"CVE-2026-98989","aliases":[],"summary":"namespace: check a recursive bind mount for mount namespace loops","details":"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.","categories":["Operating systems"],"product":"Linux","vendor":"Linux","ecosystem":null,"affected_ranges":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98989","source_modified_at":"2026-10-23T12:20:08.366Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"e149ed2b805fefdccf7ccdfc19eca22fdd4514ac","lessThan":"a0ba48256f5dff6f75a45f8ce39fe57f21df1022","status":"affected","versionType":"git"},{"version":"e149ed2b805fefdccf7ccdfc19eca22fdd4514ac","lessThan":"37a82f400efa4d263542a5fa41755b21057f1e5d","status":"affected","versionType":"git"},{"version":"e149ed2b805fefdccf7ccdfc19eca22fdd4514ac","lessThan":"c640a01a78e42302879006ed7b7d5a9a943ba815","status":"affected","versionType":"git"}],"defaultStatus":"unaffected"},{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98989","source_modified_at":"2026-10-23T12:20:08.366Z","fetched_at":"2026-10-23T18:42:43.628194Z","product":"Linux","vendor":"Linux","versions":[{"version":"3.19","status":"affected"},{"version":"0","lessThan":"3.19","status":"unaffected","versionType":"semver"},{"version":"6.18.57","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.11","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}],"defaultStatus":"affected"}],"fixed_versions":[{"source":"CVE List","source_url":"https://www.cve.org/CVERecord?id=CVE-2026-98989","source_modified_at":"2026-10-23T12:20:08.366Z","fetched_at":"2026-10-23T18:42:43.628194Z","package":{"name":"Linux","ecosystem":null},"version":"37a82f400efa4d263542a5fa41755b21057f1e5d","basis":"first unaffected version stated in the CVE record"}],"cvss":null,"severity":null,"kev":{"listed":false},"epss":{"probability":null,"percentile":null,"score_date":null},"published_at":"2026-10-23T12:20:08.366Z","modified_at":"2026-10-23T12:20:08.366Z","provenance":[{"source":"CVE List","url":"https://www.cve.org/CVERecord?id=CVE-2026-98989","fetched_at":"2026-10-23T18:42:43.628194Z","source_modified_at":"2026-10-23T12:20:08.366Z"}],"sources":["CVE List"],"references":[{"source":"CVE List","url":"https://git.kernel.org/stable/c/a0ba48256f5dff6f75a45f8ce39fe57f21df1022"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/37a82f400efa4d263542a5fa41755b21057f1e5d"},{"source":"CVE List","url":"https://git.kernel.org/stable/c/c640a01a78e42302879006ed7b7d5a9a943ba815"}],"locations":[],"motoko_assessment":{"status":"requires_architecture_review","automatic_remediation":false},"cve_state":"PUBLISHED","classification":{"method":"product-first software-layer rules","rules_version":"2.1","matched_on":"product","confidence":"heuristic","reviewed":false},"change_timestamp":"2026-10-23T12:20:08.366Z","content_hash":"ca49627db776a4c28b83ba6b36e92ec683ef2dfe30da0a9906f41f2fcc96f966"}}