{"id":"DEBIAN-CVE-2025-21884","details":"In the Linux kernel, the following vulnerability has been resolved:  net: better track kernel sockets lifetime  While kernel sockets are dismantled during pernet_operations-\u003eexit(), their freeing can be delayed by any tx packets still held in qdisc or device queues, due to skb_set_owner_w() prior calls.  This then trigger the following warning from ref_tracker_dir_exit() [1]  To fix this, make sure that kernel sockets own a reference on net-\u003epassive.  Add sk_net_refcnt_upgrade() helper, used whenever a kernel socket is converted to a refcounted one.  [1]  [  136.263918][   T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [  136.263918][   T35]      sk_alloc+0x2b3/0x370 [  136.263918][   T35]      inet6_create+0x6ce/0x10f0 [  136.263918][   T35]      __sock_create+0x4c0/0xa30 [  136.263918][   T35]      inet_ctl_sock_create+0xc2/0x250 [  136.263918][   T35]      igmp6_net_init+0x39/0x390 [  136.263918][   T35]      ops_init+0x31e/0x590 [  136.263918][   T35]      setup_net+0x287/0x9e0 [  136.263918][   T35]      copy_net_ns+0x33f/0x570 [  136.263918][   T35]      create_new_namespaces+0x425/0x7b0 [  136.263918][   T35]      unshare_nsproxy_namespaces+0x124/0x180 [  136.263918][   T35]      ksys_unshare+0x57d/0xa70 [  136.263918][   T35]      __x64_sys_unshare+0x38/0x40 [  136.263918][   T35]      do_syscall_64+0xf3/0x230 [  136.263918][   T35]      entry_SYSCALL_64_after_hwframe+0x77/0x7f [  136.263918][   T35] [  136.343488][   T35] ref_tracker: net notrefcnt@ffff8880638f01e0 has 1/2 users at [  136.343488][   T35]      sk_alloc+0x2b3/0x370 [  136.343488][   T35]      inet6_create+0x6ce/0x10f0 [  136.343488][   T35]      __sock_create+0x4c0/0xa30 [  136.343488][   T35]      inet_ctl_sock_create+0xc2/0x250 [  136.343488][   T35]      ndisc_net_init+0xa7/0x2b0 [  136.343488][   T35]      ops_init+0x31e/0x590 [  136.343488][   T35]      setup_net+0x287/0x9e0 [  136.343488][   T35]      copy_net_ns+0x33f/0x570 [  136.343488][   T35]      create_new_namespaces+0x425/0x7b0 [  136.343488][   T35]      unshare_nsproxy_namespaces+0x124/0x180 [  136.343488][   T35]      ksys_unshare+0x57d/0xa70 [  136.343488][   T35]      __x64_sys_unshare+0x38/0x40 [  136.343488][   T35]      do_syscall_64+0xf3/0x230 [  136.343488][   T35]      entry_SYSCALL_64_after_hwframe+0x77/0x7f","modified":"2026-08-27T23:05:27.045869974Z","published":"2025-03-27T15:15:56.313Z","upstream":["CVE-2025-21884"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-21884"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.43-1"}]}],"versions":["6.12.38-1","6.12.41-1","6.12.43-1~bpo12+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21884.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.16.3-1"}]}],"versions":["6.12.100-1","6.12.101-1","6.12.105-1","6.12.38-1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.85-1","6.12.85-1~bpo12+1","6.12.86-1","6.12.86-1~bpo12+1","6.12.88-1","6.12.88-1~bpo12+1","6.12.90-1","6.12.90-1~bpo12+1","6.12.90-2","6.12.90-2~bpo12+1","6.12.94-1","6.12.94-1~bpo12+1","6.12.95-1","6.12.95-1~bpo12+1","6.12.96-1","6.13.10-1~exp1","6.13.11-1~exp1","6.13.2-1~exp1","6.13.3-1~exp1","6.13.4-1~exp1","6.13.5-1~exp1","6.13.6-1~exp1","6.13.7-1~exp1","6.13.8-1~exp1","6.13.9-1~exp1","6.13~rc6-1~exp1","6.13~rc7-1~exp1","6.14.3-1~exp1","6.14.5-1~exp1","6.14.6-1~exp1","6.15-1~exp1","6.15.1-1~exp1","6.15.2-1~exp1","6.15.3-1~exp1","6.15.4-1~exp1","6.15.5-1~exp1","6.15.6-1~exp1","6.15~rc7-1~exp1","6.16-1~exp1","6.16.1-1~exp1","6.16.3-1~bpo13+1","6.16~rc7-1~exp1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-21884.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}