Summary
In the Linux kernel, the following vulnerability has been resolved: mptcp: fix disconnect vs...
In the Linux kernel, the following vulnerability has been resolved:
mptcp: fix disconnect vs accept race
Despite commit 0ad529d9fd2b ("mptcp: fix possible divide by zero in
recvmsg()"), the mptcp protocol is still prone to a race between
disconnect() (or shutdown) and accept.
The root cause is that the mentioned commit checks the msk-level
flag, but mptcp_stream_accept() does acquire the msk-level lock,
as it can rely directly on the first subflow lock.
As reported by Christoph than can lead to a race where an msk
socket is accepted after that mptcp_subflow_queue_clean() releases
the listener socket lock and just before it takes destructive
actions leading to the following splat:
BUG: kernel NULL pointer dereference, address: 0000000000000012
PGD 5a4ca067 P4D 5a4ca067 PUD 37d4c067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 2 PID: 10955 Comm: syz-executor.5 Not tainted 6.5.0-rc1-gdc7b257ee5dd #37
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
RIP: 0010:mptcp_stream_accept+0x1ee/0x2f0 include/net/inet_sock.h:330
Code: 0a 09 00 48 8b 1b 4c 39 e3 74 07 e8 bc 7c 7f fe eb a1 e8 b5 7c 7f fe 4c 8b 6c 24 08 eb 05 e8 a9 7c 7f fe 49 8b 85 d8 09 00 00 <0f> b6 40 12 88 44 24 07 0f b6 6c 24 07 bf 07 00 00 00 89 ee e8 89
RSP: 0018:ffffc90000d07dc0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888037e8d020 RCX: ffff88803b093300
RDX: 0000000000000000 RSI: ffffffff833822c5 RDI: ffffffff8333896a
RBP: 0000607f82031520 R08: ffff88803b093300 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000003e83 R12: ffff888037e8d020
R13: ffff888037e8c680 R14: ffff888009af7900 R15: ffff888009af6880
FS: 00007fc26d708640(0000) GS:ffff88807dd00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000012 CR3: 0000000066bc5001 CR4: 0000000000370ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
do_accept+0x1ae/0x260 net/socket.c:1872
__sys_accept4+0x9b/0x110 net/socket.c:1913
__do_sys_accept4 net/socket.c:1954 [inline]
__se_sys_accept4 net/socket.c:1951 [inline]
__x64_sys_accept4+0x20/0x30 net/socket.c:1951
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x47/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Address the issue by temporary removing the pending request socket
from the accept queue, so that racing accept() can't touch them.
After depleting the msk - the ssk still exists, as plain TCP sockets,
re-insert them into the accept queue, so that later inet_csk_listen_stop()
will complete the tcp socket disposal.
Impact
Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.
CVE-2023-53490 has a CVSS score of 4.7 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2023-53490? CVE-2023-53490 is a medium-severity race condition vulnerability. No fixed version is listed yet. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
- How severe is CVE-2023-53490? CVE-2023-53490 has a CVSS score of 4.7 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2023-53490? No fixed version is listed for CVE-2023-53490 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2023-53490 exploitable, and should I be worried? Whether CVE-2023-53490 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-53490 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.