{"cve":"CVE-2025-21678","nvd":{"published":"2025-01-31T12:15:28.970","modified":"2026-07-30T06:18:40.060","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ngtp: Destroy device along with udp socket's netns dismantle.\n\ngtp_newlink() links the device to a list in dev_net(dev) instead of\nsrc_net, where a udp tunnel socket is created.\n\nEven when src_net is removed, the device stays alive on dev_net(dev).\nThen, removing src_net triggers the splat below. [0]\n\nIn this example, gtp0 is created in ns2, and the udp socket is created\nin ns1.\n\n  ip netns add ns1\n  ip netns add ns2\n  ip -n ns1 link add netns ns2 name gtp0 type gtp role sgsn\n  ip netns del ns1\n\nLet's link the device to the socket's netns instead.\n\nNow, gtp_net_exit_batch_rtnl() needs another netdev iteration to remove\nall gtp devices in the netns.\n\n[0]:\nref_tracker: net notrefcnt@000000003d6e7d05 has 1/2 users at\n     sk_alloc (./include/net/net_namespace.h:345 net/core/sock.c:2236)\n     inet_create (net/ipv4/af_inet.c:326 net/ipv4/af_inet.c:252)\n     __sock_create (net/socket.c:1558)\n     udp_sock_create4 (net/ipv4/udp_tunnel_core.c:18)\n     gtp_create_sock (./include/net/udp_tunnel.h:59 drivers/net/gtp.c:1423)\n     gtp_create_sockets (drivers/net/gtp.c:1447)\n     gtp_newlink (drivers/net/gtp.c:1507)\n     rtnl_newlink (net/core/rtnetlink.c:3786 net/core/rtnetlink.c:3897 net/core/rtnetlink.c:4012)\n     rtnetlink_rcv_msg (net/core/rtnetlink.c:6922)\n     netlink_rcv_skb (net/netlink/af_netlink.c:2542)\n     netlink_unicast (net/netlink/af_netlink.c:1321 net/netlink/af_netlink.c:1347)\n     netlink_sendmsg (net/netlink/af_netlink.c:1891)\n     ____sys_sendmsg (net/socket.c:711 net/socket.c:726 net/socket.c:2583)\n     ___sys_sendmsg (net/socket.c:2639)\n     __sys_sendmsg (net/socket.c:2669)\n     do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)\n\nWARNING: CPU: 1 PID: 60 at lib/ref_tracker.c:179 ref_tracker_dir_exit (lib/ref_tracker.c:179)\nModules linked in:\nCPU: 1 UID: 0 PID: 60 Comm: kworker/u16:2 Not tainted 6.13.0-rc5-00147-g4c1224501e9d #5\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014\nWorkqueue: netns cleanup_net\nRIP: 0010:ref_tracker_dir_exit (lib/ref_tracker.c:179)\nCode: 00 00 00 fc ff df 4d 8b 26 49 bd 00 01 00 00 00 00 ad de 4c 39 f5 0f 85 df 00 00 00 48 8b 74 24 08 48 89 df e8 a5 cc 12 02 90 <0f> 0b 90 48 8d 6b 44 be 04 00 00 00 48 89 ef e8 80 de 67 ff 48 89\nRSP: 0018:ff11000009a07b60 EFLAGS: 00010286\nRAX: 0000000000002bd3 RBX: ff1100000f4e1aa0 RCX: 1ffffffff0e40ac6\nRDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8423ee3c\nRBP: ff1100000f4e1af0 R08: 0000000000000001 R09: fffffbfff0e395ae\nR10: 0000000000000001 R11: 0000000000036001 R12: ff1100000f4e1af0\nR13: dead000000000100 R14: ff1100000f4e1af0 R15: dffffc0000000000\nFS:  0000000000000000(0000) GS:ff1100006ce80000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007f9b2464bd98 CR3: 0000000005286005 CR4: 0000000000771ef0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe07f0 DR7: 0000000000000400\nPKRU: 55555554\nCall Trace:\n <TASK>\n ? __warn (kernel/panic.c:748)\n ? ref_tracker_dir_exit (lib/ref_tracker.c:179)\n ? report_bug (lib/bug.c:201 lib/bug.c:219)\n ? handle_bug (arch/x86/kernel/traps.c:285)\n ? exc_invalid_op (arch/x86/kernel/traps.c:309 (discriminator 1))\n ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621)\n ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/irqflags.h:42 ./arch/x86/include/asm/irqflags.h:97 ./arch/x86/include/asm/irqflags.h:155 ./include/linux/spinlock_api_smp.h:151 kernel/locking/spinlock.c:194)\n ? ref_tracker_dir_exit (lib/ref_tracker.c:179)\n ? __pfx_ref_tracker_dir_exit (lib/ref_tracker.c:158)\n ? kfree (mm/slub.c:4613 mm/slub.c:4761)\n net_free (net/core/net_namespace.c:476 net/core/net_namespace.c:467)\n cleanup_net (net/core/net_namespace.c:664 (discriminator 3))\n process_one_work (kernel/workqueue.c:3229)\n worker_thread (kernel/workqueue.c:3304 kernel/workqueue.c:3391\n---truncated---","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/036f8d814a2cd11ee8ef62b8f3e7ce5dec0ee4f3","https://git.kernel.org/stable/c/5f1678346109ff3a6d229d33437fcba3cce9209d","https://git.kernel.org/stable/c/86f73d4ab2f27deeff22ba9336ad103d94f12ac7","https://git.kernel.org/stable/c/bb11f992f5a475bc68ef959f17a55306f0328495","https://git.kernel.org/stable/c/c986380c1d5274c4d5e935addc807d6791cc23eb"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:58:41.599736885+00:00"},"epss":{"cve":"CVE-2025-21678","score":0.00236,"percentile":0.14588,"date":"2026-11-01"},"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."]}