CVE-2023-54176
- Published: 2025-12-30T13:16:05.470
In the Linux kernel, the following vulnerability has been resolved:
mptcp: stricter state check in mptcp_worker
As reported by Christoph, the mptcp protocol can run the
worker when the relevant msk socket is in an unexpected state:
connect()
// incoming reset + fastclose
// the mptcp worker is scheduled
mptcp_disconnect()
// msk is now CLOSED
listen()
mptcp_worker()
Leading to the following splat:
divide error: 0000 [#1] PREEMPT SMP
CPU: 1 PID: 21 Comm: kworker/1:0 Not tainted 6.3.0-rc1-gde5e8fd0123c #11
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
Workqueue: events mptcp_worker
RIP: 0010:__tcp_select_window+0x22c/0x4b0 net/ipv4/tcp_output.c:3018
RSP: 0018:ffffc900000b3c98 EFLAGS: 00010293
RAX: 000000000000ffd7 RBX: 000000000000ffd7 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff8214ce97 RDI: 0000000000000004
RBP: 000000000000ffd7 R08: 0000000000000004 R09: 0000000000010000
R10: 000000000000ffd7 R11: ffff888005afa148 R12: 000000000000ffd7
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88803ed00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000405270 CR3: 000000003011e006 CR4: 0000000000370ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
tcp_select_window net/ipv4/tcp_output.c:262 [inline]
__tcp_transmit_skb+0x356/0x1280 net/ipv4/tcp_output.c:1345
tcp_transmit_skb net/ipv4/tcp_output.c:1417 [inline]
tcp_send_active_reset+0x13e/0x320 net/ipv4/tcp_output.c:3459
mptcp_check_fastclose net/mptcp/protocol.c:2530 [inline]
mptcp_worker+0x6c7/0x800 net/mptcp/protocol.c:2705
process_one_work+0x3bd/0x950 kernel/workqueue.c:2390
worker_thread+0x5b/0x610 kernel/workqueue.c:2537
kthread+0x138/0x170 kernel/kthread.c:376
ret_from_fork+0x2c/0x50 arch/x86/entry/entry_64.S:308
This change addresses the issue explicitly checking for bad states
before running the mptcp worker.
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How to fix CVE-2023-54176
Description: In the Linux kernel, the following vulnerability has been resolved: mptcp: stricter state check in mptcp_worker As reported by Christoph, the mptcp protocol can run the worker when the relevant msk socket is in an unexpected state: connect() // incoming reset + fastclose // the mptcp worker is scheduled mptcp_disconnect() // msk is now CLOSED […]
Exploit Difficulty: HARD
⏱️ Time to exploit: > 4 hours
🛠️ Required skills: Advanced security expertise
💰 Public exploits: Rare or not public
How to Fix:
- Check if you're running the affected product
- Update to the latest patched version
- If patching is not immediately possible: restrict network exposure, apply least-privilege access
- Test the fix in a staging environment first
- Review logs for signs of exploitation
- Monitor for IOCs (Indicators of Compromise)
- Enable automatic security updates
- Set up vulnerability monitoring
- Review and harden security configurations
Exploit Difficulty Assessment
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