{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2025-21677",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2024-12-29T08:45:45.738Z",
        "datePublished": "2025-01-31T11:25:38.809Z",
        "dateUpdated": "2026-08-05T11:53:33.356Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-08-05T11:53:33.356Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npfcp: Destroy device along with udp socket's netns dismantle.\n\npfcp_newlink() links the device to a list in dev_net(dev) instead\nof net, where a udp tunnel socket is created.\n\nEven when net is removed, the device stays alive on dev_net(dev).\nThen, removing net triggers the splat below. [0]\n\nIn this example, pfcp0 is created in ns2, but the udp socket is\ncreated in ns1.\n\n  ip netns add ns1\n  ip netns add ns2\n  ip -n ns1 link add netns ns2 name pfcp0 type pfcp\n  ip netns del ns1\n\nLet's link the device to the socket's netns instead.\n\nNow, pfcp_net_exit() needs another netdev iteration to remove\nall pfcp devices in the netns.\n\npfcp_dev_list is not used under RCU, so the list API is converted\nto the non-RCU variant.\n\npfcp_net_exit() can be converted to .exit_batch_rtnl() in net-next.\n\n[0]:\nref_tracker: net notrefcnt@00000000128b34dc has 1/1 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     pfcp_create_sock (drivers/net/pfcp.c:168)\n     pfcp_newlink (drivers/net/pfcp.c:182 drivers/net/pfcp.c:197)\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     entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)\n\nWARNING: CPU: 1 PID: 11 at lib/ref_tracker.c:179 ref_tracker_dir_exit (lib/ref_tracker.c:179)\nModules linked in:\nCPU: 1 UID: 0 PID: 11 Comm: kworker/u16:0 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:ff11000007f3fb60 EFLAGS: 00010286\nRAX: 00000000000020ef RBX: ff1100000d6481e0 RCX: 1ffffffff0e40d82\nRDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8423ee3c\nRBP: ff1100000d648230 R08: 0000000000000001 R09: fffffbfff0e395af\nR10: 0000000000000001 R11: 0000000000000000 R12: ff1100000d648230\nR13: dead000000000100 R14: ff1100000d648230 R15: dffffc0000000000\nFS:  0000000000000000(0000) GS:ff1100006ce80000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00005620e1363990 CR3: 000000000eeb2002 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/cor\n---truncated---"
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "version": "3.1",
                        "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                        "baseScore": 7.8,
                        "baseSeverity": "HIGH"
                    },
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "AV:L - The vulnerability is triggered exclusively through RTM_NEWLINK rtnetlink messages and netns creation/destruction from local syscalls; there is no remote packet path into pfcp_newlink().\nAC:L - The trigger is a fully deterministic four-command sequence (create two netns, create a pfcp link cross-netns, delete the socket's netns) with no race and no dependence on conditions outside the attacker's control; heap grooming of the freed net_cachep object is done simply by creating further namespaces.\nPR:L - CAP_NET_ADMIN over both netns is required, but an unprivileged user obtains it via `unshare -Urn` since both namespaces are owned by their own user namespace, satisfying netlink_net_capable() and rtnl_link_get_net_capable(); the pfcp module is auto-loaded via its rtnl-link alias.\nUI:N - The attacker performs the entire sequence itself through netlink and namespace syscalls; no victim action is involved.\nS:U - The corruption stays within the kernel's own security authority — a standard kernel memory-safety issue with no VM, IOMMU, or hypervisor boundary crossed.\nC:H - The dangling socket reads pointers (`net->ipv4.udp_table`, `net->core.prot_inuse`, `net_hash_mix()`) out of the freed and potentially reallocated `struct net`, giving a use-after-free read that can be leveraged to disclose kernel memory.\nI:H - udp_lib_unhash() and __netns_tracker_free() perform spinlock acquisition, list unlinking, and per-cpu increments on the freed netns object, yielding a write primitive at attacker-influenceable addresses once the slab slot is re-groomed with a new namespace.\nA:H - Deleting the socket's netns immediately produces a ref_tracker WARNING in cleanup_net (a panic under panic_on_warn) and permanently leaks the netdevice and socket, with the subsequent use-after-free reliably causing kernel corruption and crashes."
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "drivers/net/pfcp.c"
                    ],
                    "versions": [
                        {
                            "version": "76c8764ef36a5d37ea2e551bda28ac7f028383ba",
                            "lessThan": "1c35a66e2bfea53dea3562b2575ac7fd4c38ee61",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "76c8764ef36a5d37ea2e551bda28ac7f028383ba",
                            "lessThan": "ffc90e9ca61b0f619326a1417ff32efd6cc71ed2",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "drivers/net/pfcp.c"
                    ],
                    "versions": [
                        {
                            "version": "6.10",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.10",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.11",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.13",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.10",
                                    "versionEndExcluding": "6.12.11"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "6.10",
                                    "versionEndExcluding": "6.13"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/1c35a66e2bfea53dea3562b2575ac7fd4c38ee61"
                },
                {
                    "url": "https://git.kernel.org/stable/c/ffc90e9ca61b0f619326a1417ff32efd6cc71ed2"
                }
            ],
            "title": "pfcp: Destroy device along with udp socket's netns dismantle.",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        }
    }
}