{"cve":"CVE-2025-21875","nvd":{"published":"2025-03-27T15:15:55.307","modified":"2026-10-15T22:18:10.493","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmptcp: always handle address removal under msk socket lock\n\nSyzkaller reported a lockdep splat in the PM control path:\n\n  WARNING: CPU: 0 PID: 6693 at ./include/net/sock.h:1711 sock_owned_by_me include/net/sock.h:1711 [inline]\n  WARNING: CPU: 0 PID: 6693 at ./include/net/sock.h:1711 msk_owned_by_me net/mptcp/protocol.h:363 [inline]\n  WARNING: CPU: 0 PID: 6693 at ./include/net/sock.h:1711 mptcp_pm_nl_addr_send_ack+0x57c/0x610 net/mptcp/pm_netlink.c:788\n  Modules linked in:\n  CPU: 0 UID: 0 PID: 6693 Comm: syz.0.205 Not tainted 6.14.0-rc2-syzkaller-00303-gad1b832bf1cf #0\n  Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024\n  RIP: 0010:sock_owned_by_me include/net/sock.h:1711 [inline]\n  RIP: 0010:msk_owned_by_me net/mptcp/protocol.h:363 [inline]\n  RIP: 0010:mptcp_pm_nl_addr_send_ack+0x57c/0x610 net/mptcp/pm_netlink.c:788\n  Code: 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc e8 ca 7b d3 f5 eb b9 e8 c3 7b d3 f5 90 0f 0b 90 e9 dd fb ff ff e8 b5 7b d3 f5 90 <0f> 0b 90 e9 3e fb ff ff 44 89 f1 80 e1 07 38 c1 0f 8c eb fb ff ff\n  RSP: 0000:ffffc900034f6f60 EFLAGS: 00010283\n  RAX: ffffffff8bee3c2b RBX: 0000000000000001 RCX: 0000000000080000\n  RDX: ffffc90004d42000 RSI: 000000000000a407 RDI: 000000000000a408\n  RBP: ffffc900034f7030 R08: ffffffff8bee37f6 R09: 0100000000000000\n  R10: dffffc0000000000 R11: ffffed100bcc62e4 R12: ffff88805e6316e0\n  R13: ffff88805e630c00 R14: dffffc0000000000 R15: ffff88805e630c00\n  FS:  00007f7e9a7e96c0(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 0000001b2fd18ff8 CR3: 0000000032c24000 CR4: 00000000003526f0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   <TASK>\n   mptcp_pm_remove_addr+0x103/0x1d0 net/mptcp/pm.c:59\n   mptcp_pm_remove_anno_addr+0x1f4/0x2f0 net/mptcp/pm_netlink.c:1486\n   mptcp_nl_remove_subflow_and_signal_addr net/mptcp/pm_netlink.c:1518 [inline]\n   mptcp_pm_nl_del_addr_doit+0x118d/0x1af0 net/mptcp/pm_netlink.c:1629\n   genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline]\n   genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]\n   genl_rcv_msg+0xb1f/0xec0 net/netlink/genetlink.c:1210\n   netlink_rcv_skb+0x206/0x480 net/netlink/af_netlink.c:2543\n   genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219\n   netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline]\n   netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1348\n   netlink_sendmsg+0x8de/0xcb0 net/netlink/af_netlink.c:1892\n   sock_sendmsg_nosec net/socket.c:718 [inline]\n   __sock_sendmsg+0x221/0x270 net/socket.c:733\n   ____sys_sendmsg+0x53a/0x860 net/socket.c:2573\n   ___sys_sendmsg net/socket.c:2627 [inline]\n   __sys_sendmsg+0x269/0x350 net/socket.c:2659\n   do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n  RIP: 0033:0x7f7e9998cde9\n  Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48\n  RSP: 002b:00007f7e9a7e9038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e\n  RAX: ffffffffffffffda RBX: 00007f7e99ba5fa0 RCX: 00007f7e9998cde9\n  RDX: 000000002000c094 RSI: 0000400000000000 RDI: 0000000000000007\n  RBP: 00007f7e99a0e2a0 R08: 0000000000000000 R09: 0000000000000000\n  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\n  R13: 0000000000000000 R14: 00007f7e99ba5fa0 R15: 00007fff49231088\n\nIndeed the PM can try to send a RM_ADDR over a msk without acquiring\nfirst the msk socket lock.\n\nThe bugged code-path comes from an early optimization: when there\nare no subflows, the PM should (usually) not send RM_ADDR\nnotifications.\n\nThe above statement is incorrect, as without locks another process\ncould concur\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/2c3de6dff4373f1036e003f49a32629359530bdb","https://git.kernel.org/stable/c/4124b782ec2b1e2e490cf0bbf10f53dfd3479890","https://git.kernel.org/stable/c/494ec285535632732eaa5786297a9ae4f731b5ff","https://git.kernel.org/stable/c/7cca31035c05819643ffb5d7518e9a331b3f6651","https://git.kernel.org/stable/c/8116fb4acd5d3f06cd37f84887dbe962b6703b1c"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:00:28.034033815+00:00"},"epss":{"cve":"CVE-2025-21875","score":0.00228,"percentile":0.13437,"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."]}