{"id":"AZL-73896","summary":"CVE-2025-38721 affecting package kernel for versions less than 5.15.200.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ctnetlink: fix refcount leak on table dump\n\nThere is a reference count leak in ctnetlink_dump_table():\n      if (res \u003c 0) {\n                nf_conntrack_get(&ct-\u003ect_general); // HERE\n                cb-\u003eargs[1] = (unsigned long)ct;\n                ...\n\nWhile its very unlikely, its possible that ct == last.\nIf this happens, then the refcount of ct was already incremented.\nThis 2nd increment is never undone.\n\nThis prevents the conntrack object from being released, which in turn\nkeeps prevents cnet-\u003ecount from dropping back to 0.\n\nThis will then block the netns dismantle (or conntrack rmmod) as\nnf_conntrack_cleanup_net_list() will wait forever.\n\nThis can be reproduced by running conntrack_resize.sh selftest in a loop.\nIt takes ~20 minutes for me on a preemptible kernel on average before\nI see a runaway kworker spinning in nf_conntrack_cleanup_net_list.\n\nOne fix would to change this to:\n        if (res \u003c 0) {\n\t\tif (ct != last)\n\t                nf_conntrack_get(&ct-\u003ect_general);\n\nBut this reference counting isn't needed in the first place.\nWe can just store a cookie value instead.\n\nA followup patch will do the same for ctnetlink_exp_dump_table,\nit looks to me as if this has the same problem and like\nctnetlink_dump_table, we only need a 'skip hint', not the actual\nobject so we can apply the same cookie strategy there as well.","modified":"2026-04-01T05:22:21.272531Z","published":"2025-09-04T16:15:41Z","upstream":["CVE-2025-38721"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38721"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:2","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.200.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-73896.json"}}],"schema_version":"1.7.5"}