{"cve":"CVE-2025-21884","nvd":{"published":"2025-03-27T15:15:56.313","modified":"2026-10-15T22:18:10.910","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: better track kernel sockets lifetime\n\nWhile kernel sockets are dismantled during pernet_operations->exit(),\ntheir freeing can be delayed by any tx packets still held in qdisc\nor device queues, due to skb_set_owner_w() prior calls.\n\nThis then trigger the following warning from ref_tracker_dir_exit() [1]\n\nTo fix this, make sure that kernel sockets own a reference on net->passive.\n\nAdd sk_net_refcnt_upgrade() helper, used whenever a kernel socket\nis converted to a refcounted one.\n\n[1]\n\n[  136.263918][   T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at\n[  136.263918][   T35]      sk_alloc+0x2b3/0x370\n[  136.263918][   T35]      inet6_create+0x6ce/0x10f0\n[  136.263918][   T35]      __sock_create+0x4c0/0xa30\n[  136.263918][   T35]      inet_ctl_sock_create+0xc2/0x250\n[  136.263918][   T35]      igmp6_net_init+0x39/0x390\n[  136.263918][   T35]      ops_init+0x31e/0x590\n[  136.263918][   T35]      setup_net+0x287/0x9e0\n[  136.263918][   T35]      copy_net_ns+0x33f/0x570\n[  136.263918][   T35]      create_new_namespaces+0x425/0x7b0\n[  136.263918][   T35]      unshare_nsproxy_namespaces+0x124/0x180\n[  136.263918][   T35]      ksys_unshare+0x57d/0xa70\n[  136.263918][   T35]      __x64_sys_unshare+0x38/0x40\n[  136.263918][   T35]      do_syscall_64+0xf3/0x230\n[  136.263918][   T35]      entry_SYSCALL_64_after_hwframe+0x77/0x7f\n[  136.263918][   T35]\n[  136.343488][   T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at\n[  136.343488][   T35]      sk_alloc+0x2b3/0x370\n[  136.343488][   T35]      inet6_create+0x6ce/0x10f0\n[  136.343488][   T35]      __sock_create+0x4c0/0xa30\n[  136.343488][   T35]      inet_ctl_sock_create+0xc2/0x250\n[  136.343488][   T35]      ndisc_net_init+0xa7/0x2b0\n[  136.343488][   T35]      ops_init+0x31e/0x590\n[  136.343488][   T35]      setup_net+0x287/0x9e0\n[  136.343488][   T35]      copy_net_ns+0x33f/0x570\n[  136.343488][   T35]      create_new_namespaces+0x425/0x7b0\n[  136.343488][   T35]      unshare_nsproxy_namespaces+0x124/0x180\n[  136.343488][   T35]      ksys_unshare+0x57d/0xa70\n[  136.343488][   T35]      __x64_sys_unshare+0x38/0x40\n[  136.343488][   T35]      do_syscall_64+0xf3/0x230\n[  136.343488][   T35]      entry_SYSCALL_64_after_hwframe+0x77/0x7f","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/2668e038800b946d269f96ec1b258c01930a242c","https://git.kernel.org/stable/c/4ceb0bd4ffd009821b585ce6a8033b12b59fb5fb","https://git.kernel.org/stable/c/5c70eb5c593d64d93b178905da215a9fd288a4b5","https://git.kernel.org/stable/c/c31a732fac46b00b95b78fcc9c37cb48dd6f2e0c"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:00:28.034033815+00:00"},"epss":{"cve":"CVE-2025-21884","score":0.00217,"percentile":0.12062,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}