Critical 9.4Published Aug 16, 2025

CVE-2025-38552mptcp: plug races between subflow fail and subflow creation

Updated under an hour ago (Oct 26, 2026, 5:10 PM ET)

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It affects Linux and 3 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: mptcp: plug races between subflow fail and subflow creation We have races similar to the one addressed by the previous patch between subflow failing and additional subflow creation. They are just harder to trigger. The solution is similar. Use a separate flag to track the condition 'socket state prevent any additional subflow creation' protected by the fallback lock. The socket fallback makes such flag true, and also receiving or sending an MP_FAIL option. The field 'allow_infinite_fallback' is now always touched under the relevant lock, we can drop the ONCE annotation on write.

CVSS: 9.4 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 15, 2026
First seen by InfoSec Signals: Oct 15, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 478d770008b03ed9d74bdc8add2315b7fd124ecc before c476d627584b7589a134a8b48dd5c6639e4401c5; 478d770008b03ed9d74bdc8add2315b7fd124ecc builds before 7c96d519ee15a130842a6513530b4d20acd2bfcd; from 478d770008b03ed9d74bdc8add2315b7fd124ecc before f81b6fbe13c7fc413b5158cdffc6a59391a2a8db; from 478d770008b03ed9d74bdc8add2315b7fd124ecc before 659da22dee5ff316ba63bdaeeac7b58b5442f6c2; from 478d770008b03ed9d74bdc8add2315b7fd124ecc before def5b7b2643ebba696fc60ddf675dca13f073486	CNA record
Siemens SIMATIC CN 4100 siemens:simatic_cn_4100 (from the name)	before V5.0	CISA ADP
linux linux_kernel linux:linux_kernel	from 5.15 before 6.1.149; from 6.2 before 6.6.101; from 6.7 before 6.12.40; from 6.13 before 6.15.8; 6.16; 6.16; 6.16; 6.16; and 2 more ranges	NVD
debian debian_linux debian:debian_linux	11.0	NVD

References

References

https://git.kernel.org/stable/c/c476d627584b7589a134a8b48dd5c6639e4401c5	patch
https://git.kernel.org/stable/c/7c96d519ee15a130842a6513530b4d20acd2bfcd	patch
https://git.kernel.org/stable/c/f81b6fbe13c7fc413b5158cdffc6a59391a2a8db	patch
https://git.kernel.org/stable/c/659da22dee5ff316ba63bdaeeac7b58b5442f6c2	patch
https://git.kernel.org/stable/c/def5b7b2643ebba696fc60ddf675dca13f073486	patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html	mailing-list, third-party-advisory
https://cert-portal.siemens.com/productcert/html/ssa-032379.html

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.