{"id":"DEBIAN-CVE-2026-23321","details":"In the Linux kernel, the following vulnerability has been resolved:  mptcp: pm: in-kernel: always mark signal+subflow endp as used  Syzkaller managed to find a combination of actions that was generating this warning:    msk-\u003epm.local_addr_used == 0   WARNING: net/mptcp/pm_kernel.c:1071 at __mark_subflow_endp_available net/mptcp/pm_kernel.c:1071 [inline], CPU#1: syz.2.17/961   WARNING: net/mptcp/pm_kernel.c:1071 at mptcp_nl_remove_subflow_and_signal_addr net/mptcp/pm_kernel.c:1103 [inline], CPU#1: syz.2.17/961   WARNING: net/mptcp/pm_kernel.c:1071 at mptcp_pm_nl_del_addr_doit+0x81d/0x8f0 net/mptcp/pm_kernel.c:1210, CPU#1: syz.2.17/961   Modules linked in:   CPU: 1 UID: 0 PID: 961 Comm: syz.2.17 Not tainted 6.19.0-08368-gfafda3b4b06b #22 PREEMPT(full)   Hardware name: QEMU Ubuntu 25.10 PC v2 (i440FX + PIIX, + 10.1 machine, 1996), BIOS 1.17.0-debian-1.17.0-1build1 04/01/2014   RIP: 0010:__mark_subflow_endp_available net/mptcp/pm_kernel.c:1071 [inline]   RIP: 0010:mptcp_nl_remove_subflow_and_signal_addr net/mptcp/pm_kernel.c:1103 [inline]   RIP: 0010:mptcp_pm_nl_del_addr_doit+0x81d/0x8f0 net/mptcp/pm_kernel.c:1210   Code: 89 c5 e8 46 30 6f fe e9 21 fd ff ff 49 83 ed 80 e8 38 30 6f fe 4c 89 ef be 03 00 00 00 e8 db 49 df fe eb ac e8 24 30 6f fe 90 \u003c0f\u003e 0b 90 e9 1d ff ff ff e8 16 30 6f fe eb 05 e8 0f 30 6f fe e8 9a   RSP: 0018:ffffc90001663880 EFLAGS: 00010293   RAX: ffffffff82de1a6c RBX: 0000000000000000 RCX: ffff88800722b500   RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000   RBP: ffff8880158b22d0 R08: 0000000000010425 R09: ffffffffffffffff   R10: ffffffff82de18ba R11: 0000000000000000 R12: ffff88800641a640   R13: ffff8880158b1880 R14: ffff88801ec3c900 R15: ffff88800641a650   FS:  00005555722c3500(0000) GS:ffff8880f909d000(0000) knlGS:0000000000000000   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033   CR2: 00007f66346e0f60 CR3: 000000001607c000 CR4: 0000000000350ef0   Call Trace:    \u003cTASK\u003e    genl_family_rcv_msg_doit+0x117/0x180 net/netlink/genetlink.c:1115    genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]    genl_rcv_msg+0x3a8/0x3f0 net/netlink/genetlink.c:1210    netlink_rcv_skb+0x16d/0x240 net/netlink/af_netlink.c:2550    genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219    netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]    netlink_unicast+0x3e9/0x4c0 net/netlink/af_netlink.c:1344    netlink_sendmsg+0x4aa/0x5b0 net/netlink/af_netlink.c:1894    sock_sendmsg_nosec net/socket.c:727 [inline]    __sock_sendmsg+0xc9/0xf0 net/socket.c:742    ____sys_sendmsg+0x272/0x3b0 net/socket.c:2592    ___sys_sendmsg+0x2de/0x320 net/socket.c:2646    __sys_sendmsg net/socket.c:2678 [inline]    __do_sys_sendmsg net/socket.c:2683 [inline]    __se_sys_sendmsg net/socket.c:2681 [inline]    __x64_sys_sendmsg+0x110/0x1a0 net/socket.c:2681    do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]    do_syscall_64+0x143/0x440 arch/x86/entry/syscall_64.c:94    entry_SYSCALL_64_after_hwframe+0x77/0x7f   RIP: 0033:0x7f66346f826d   Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 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 \u003c48\u003e 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48   RSP: 002b:00007ffc83d8bdc8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e   RAX: ffffffffffffffda RBX: 00007f6634985fa0 RCX: 00007f66346f826d   RDX: 00000000040000b0 RSI: 0000200000000740 RDI: 0000000000000007   RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000   R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6634985fa8   R13: 00007f6634985fac R14: 0000000000000000 R15: 0000000000001770    \u003c/TASK\u003e  The actions that caused that seem to be:   - Set the MPTCP subflows limit to 0  - Create an MPTCP endpoint with both the 'signal' and 'subflow' flags  - Create a new MPTCP connection from a different address: an ADD_ADDR    linked to the MPTCP endpoint will be sent ('signal' flag), but no    subflows is initiated ('subflow' flag)  - Remove the MPTCP endpoint  ---truncated---","modified":"2026-09-01T16:06:35.205447247Z","published":"2026-03-25T11:16:28.900Z","upstream":["CVE-2026-23321"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-23321"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.170-1"}]}],"versions":["6.1.106-1","6.1.106-2","6.1.106-3","6.1.112-1","6.1.115-1","6.1.119-1","6.1.123-1","6.1.124-1","6.1.128-1","6.1.129-1","6.1.133-1","6.1.135-1","6.1.137-1","6.1.139-1","6.1.140-1","6.1.147-1","6.1.148-1","6.1.153-1","6.1.158-1","6.1.159-1","6.1.162-1","6.1.164-1","6.1.27-1","6.1.37-1","6.1.38-1","6.1.38-2","6.1.38-2~bpo11+1","6.1.38-3","6.1.38-4","6.1.38-4~bpo11+1","6.1.52-1","6.1.55-1","6.1.55-1~bpo11+1","6.1.64-1","6.1.66-1","6.1.67-1","6.1.69-1","6.1.69-1~bpo11+1","6.1.76-1","6.1.76-1~bpo11+1","6.1.82-1","6.1.85-1","6.1.90-1","6.1.90-1~bpo11+1","6.1.94-1","6.1.94-1~bpo11+1","6.1.98-1","6.1.99-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-23321.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.85-1"}]}],"versions":["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~bpo12+1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-23321.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.19.8-1"}]}],"versions":["6.12.100-1","6.12.101-1","6.12.105-1","6.12.107-1","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","6.16.10-1","6.16.11-1","6.16.12-1","6.16.12-1~bpo13+1","6.16.12-2","6.16.3-1","6.16.3-1~bpo13+1","6.16.5-1","6.16.6-1","6.16.7-1","6.16.8-1","6.16.9-1","6.16~rc7-1~exp1","6.17.10-1","6.17.11-1","6.17.12-1","6.17.13-1","6.17.13-1~bpo13+1","6.17.2-1~exp1","6.17.5-1~exp1","6.17.6-1","6.17.7-1","6.17.7-2","6.17.8-1","6.17.8-1~bpo13+1","6.17.9-1","6.18.1-1~exp1","6.18.10-1","6.18.12-1","6.18.12-1~bpo13+1","6.18.13-1","6.18.14-1","6.18.15-1","6.18.15-1~bpo13+1","6.18.2-1~exp1","6.18.3-1","6.18.5-1","6.18.5-1~bpo13+1","6.18.8-1","6.18.9-1","6.18.9-1~bpo13+1","6.18~rc4-1~exp1","6.18~rc4-1~exp2","6.18~rc5-1~exp1","6.18~rc6-1~exp1","6.18~rc7-1~exp1","6.19-1~exp1","6.19.2-1~exp1","6.19.3-1~exp1","6.19.4-1~exp1","6.19.5-1~exp1","6.19.6-1","6.19.6-2","6.19.6-2~bpo13+1","6.19.8-1~bpo13+1","6.19~rc4-1~exp1","6.19~rc5-1~exp1","6.19~rc6-1~exp1","6.19~rc7-1~exp1","6.19~rc8-1~exp1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-23321.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"}]}