{"id":"CVE-2026-99172","aliases":[],"title":"ipc: drop the mqueue mount with kern_unmount() on setup failure","titleSource":"Linux","descriptionSource":"Linux","products":[{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"dc55e35f9e810f23dd69cfdc91a3d636023f57a2","status":"affected","lessThan":"c0620b648321fff654173d238d4a85298ea16d05","versionType":"git"},{"version":"dc55e35f9e810f23dd69cfdc91a3d636023f57a2","status":"affected","lessThan":"f0e48172a59e517e613b73f73cc35f24fd123aeb","versionType":"git"}],"defaultStatus":"unaffected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99172"},{"vendor":"Linux","name":"Linux","platforms":[],"versions":[{"version":"5.19","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.19","versionType":"semver"},{"version":"7.2.13","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"defaultStatus":"affected","source":"Linux","url":"https://www.cve.org/CVERecord?id=CVE-2026-99172"}],"remediation":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipc: drop the mqueue mount with kern_unmount() on setup failure\n\nmq_init_ns() creates the mqueue mount with fc_mount_longterm(), so its\n->mnt_ns is MNT_NS_INTERNAL. When setting up the mqueue or ipc sysctls\nor msg_init_ns() fails afterwards, create_ipc_ns() drops it with a plain\nmntput(). With ->mnt_ns set that takes the fast path of\nmntput_no_expire(). The count drops to zero and nothing ever kills the\nmount, so the mount and the mqueue superblock are leaked.\n\nCommit dc55e35f9e81 (\"ipc: Store mqueue sysctls in the ipc namespace\")\nadded the first failure path after mq_init_ns() and never dropped the\nmount. Commit 7229d74e5e8c (\"ipc: create_ipc_ns: drop mqueue mount on\nsysctl setup failure\") tried to fix that with a mntput() but that\ndoesn't help for a long-term mount.\n\nUse kern_unmount(). free_ipc() open-codes the same thing for a namespace\nthat made it.","severity":"unknown","score":null,"published":"2026-10-28T10:35:27.245Z","modified":"2026-10-28T10:35:27.245Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://git.kernel.org/stable/c/c0620b648321fff654173d238d4a85298ea16d05","https://git.kernel.org/stable/c/f0e48172a59e517e613b73f73cc35f24fd123aeb"],"sources":[{"name":"CVE","id":"CVE-2026-99172","modified":"2026-10-28T10:35:27.245Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-99172"}],"assessments":[],"sourceAffected":[],"kev":{"status":"not-listed","checkedAt":"2026-10-29T02:20:33.012Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}