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CVE-2026-23321— mptcp: pm: in-kernel: always mark signal+subflow endp as used

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未正确标记信号和子流端点，可能导致内核警告。

AI Predicted 4.4 Difficulty: Hard EPSS 0.13% · P2

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux d93cf38fad9f66397093432b8917971a92ee0146< c5c877e140e5f46023a74a51e577ce5edd0a4be7 affected
64815ba15880ce5f99df075fa4104fef170ac7e5< 05799c2f1ca5eb13d65764dda688d02021b65e06 affected
85df533a787bf07bf4367ce2a02b822ff1fba1a3< 67f34ab318807989b57dfdb0f79e2d4e57018290 affected
85df533a787bf07bf4367ce2a02b822ff1fba1a3< a64aa7db39392add5be09dffaedbf1f0ce5554df affected
85df533a787bf07bf4367ce2a02b822ff1fba1a3< 198824ccfa64ffebd918bf99c939bd8170a4a4d8 affected
85df533a787bf07bf4367ce2a02b822ff1fba1a3< 579a752464a64cb5f9139102f0e6b90a1f595ceb affected
0f21cc29bc13e86512621727a4388c8a7ad2716b affected
6.1.106< 6.1.167 affected
… +10 more rows
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I. Basic Information for CVE-2026-23321

Vulnerability Information
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Vulnerability Title
mptcp: pm: in-kernel: always mark signal+subflow endp as used
Source: CVE Program / CVE List V5
Vulnerability Description
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->pm.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 <0f> 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: <TASK> 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 <48> 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 </TASK> 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---
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于未正确标记信号和子流端点，可能导致内核警告。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux d93cf38fad9f66397093432b8917971a92ee0146 ~ c5c877e140e5f46023a74a51e577ce5edd0a4be7 -
Linux Linux 6.11 -

II. Public POCs for CVE-2026-23321

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III. Intelligence Information for CVE-2026-23321

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Patches & Fixes for CVE-2026-23321 (6)

Same Patch Batch · Linux · 2026-03-25 · 116 CVEs total

CVE-2026-23395 8.8 HIGH Bluetooth: L2CAP: Fix accepting multiple L2CAP_ECRED_CONN_REQ
CVE-2026-31788 8.2 HIGH xen/privcmd: restrict usage in unprivileged domU
CVE-2026-23280 7.8 HIGH accel/amdxdna: Prevent ubuf size overflow
CVE-2026-23317 7.8 HIGH drm/vmwgfx: Return the correct value in vmw_translate_ptr functions
CVE-2026-23393 7.8 HIGH bridge: cfm: Fix race condition in peer_mep deletion
CVE-2026-23392 7.8 HIGH netfilter: nf_tables: release flowtable after rcu grace period on error
CVE-2026-23391 7.8 HIGH netfilter: xt_CT: drop pending enqueued packets on template removal
CVE-2026-23340 7.8 HIGH net: sched: avoid qdisc_reset_all_tx_gt() vs dequeue race for lockless qdiscs
CVE-2026-23306 7.8 HIGH scsi: pm8001: Fix use-after-free in pm8001_queue_command()
CVE-2026-23372 7.8 HIGH nfc: rawsock: cancel tx_work before socket teardown
CVE-2026-23288 7.8 HIGH accel/amdxdna: Fix out-of-bounds memset in command slot handling
CVE-2026-23378 7.8 HIGH net/sched: act_ife: Fix metalist update behavior
CVE-2026-23336 7.8 HIGH wifi: cfg80211: cancel rfkill_block work in wiphy_unregister()
CVE-2026-23351 7.8 HIGH netfilter: nft_set_pipapo: split gc into unlink and reclaim phase
CVE-2026-23383 7.8 HIGH bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
CVE-2026-23350 7.8 HIGH drm/xe/queue: Call fini on exec queue creation fail
CVE-2026-23364 7.4 HIGH ksmbd: Compare MACs in constant time
CVE-2026-23294 7.0 HIGH bpf: Fix race in devmap on PREEMPT_RT
CVE-2026-23358 drm/amdgpu: Fix error handling in slot reset
CVE-2026-23357 can: mcp251x: fix deadlock in error path of mcp251x_open

Showing top 20 of 116 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-23321

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