{"id":"CVE-2026-99172","title":"ipc: drop the mqueue mount with kern_unmount() on setup failure","summary":"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. Whe…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= dc55e35f9e810f23dd69cfdc91a3d636023f57a2 < c0620b648321fff654173d238d4a85298ea16d05","Linux >= dc55e35f9e810f23dd69cfdc91a3d636023f57a2 < f0e48172a59e517e613b73f73cc35f24fd123aeb","Linux 5.19"],"published":"2026-10-28","updated":"2026-10-28","sourceUpdated":"2026-10-28T10:35:27.245Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-99172","references":[{"url":"https://git.kernel.org/stable/c/c0620b648321fff654173d238d4a85298ea16d05"},{"url":"https://git.kernel.org/stable/c/f0e48172a59e517e613b73f73cc35f24fd123aeb"}],"tags":["cve.org"],"ingestedAt":"2026-10-28T11:09:40.386Z","slug":"CVE-2026-99172","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= dc55e35f9e810f23dd69cfdc91a3d636023f57a2 < c0620b648321fff654173d238d4a85298ea16d05`\n- `Linux >= dc55e35f9e810f23dd69cfdc91a3d636023f57a2 < f0e48172a59e517e613b73f73cc35f24fd123aeb`\n- `Linux 5.19`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}