{"id":"CVE-2026-99172","state":"PUBLISHED","title":"ipc: drop the mqueue mount with kern_unmount() on setup failure","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.","publishedAt":"2026-10-28T10:35:27.245Z","updatedAt":"2026-10-28T10:35:27.245Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"dc55e35f9e810f23dd69cfdc91a3d636023f57a2","status":"affected","lessThan":"c0620b648321fff654173d238d4a85298ea16d05","versionType":"git"},{"version":"dc55e35f9e810f23dd69cfdc91a3d636023f57a2","status":"affected","lessThan":"f0e48172a59e517e613b73f73cc35f24fd123aeb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["ipc/namespace.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","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"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["ipc/namespace.c"]}],"references":["https://git.kernel.org/stable/c/c0620b648321fff654173d238d4a85298ea16d05","https://git.kernel.org/stable/c/f0e48172a59e517e613b73f73cc35f24fd123aeb"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/99xxx/CVE-2026-99172.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-99172","state":"PUBLISHED","datePublished":"2026-10-28T10:35:27.245Z","dateUpdated":"2026-10-28T10:35:27.245Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.399Z"},"containers":{"cna":{"title":"ipc: drop the mqueue mount with kern_unmount() on setup failure","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"dc55e35f9e810f23dd69cfdc91a3d636023f57a2","status":"affected","lessThan":"c0620b648321fff654173d238d4a85298ea16d05","versionType":"git"},{"version":"dc55e35f9e810f23dd69cfdc91a3d636023f57a2","status":"affected","lessThan":"f0e48172a59e517e613b73f73cc35f24fd123aeb","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["ipc/namespace.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","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"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["ipc/namespace.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/c0620b648321fff654173d238d4a85298ea16d05"},{"url":"https://git.kernel.org/stable/c/f0e48172a59e517e613b73f73cc35f24fd123aeb"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-28T10:35:27.245Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"7.2.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.19","versionEndExcluding":"7.3"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}