CVE-2025-38552

mptcp: plug races between subflow fail and subflow creation

State: Published
Severity: 9.4 Critical
Published: Aug 16, 2025
Updated: Oct 15, 2026
Reserved: Apr 16, 2025

Description

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.

Scores

CVSS	Score	Vector	Source
3.1	9.4 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	478d770008b03ed9d74bdc8add2315b7fd124ecc to before c476d627584b7589a134a8b48dd5c6639e4401c5Affected 478d770008b03ed9d74bdc8add2315b7fd124ecc to before 7c96d519ee15a130842a6513530b4d20acd2bfcdAffected 478d770008b03ed9d74bdc8add2315b7fd124ecc to before f81b6fbe13c7fc413b5158cdffc6a59391a2a8dbAffected 478d770008b03ed9d74bdc8add2315b7fd124ecc to before 659da22dee5ff316ba63bdaeeac7b58b5442f6c2Affected 478d770008b03ed9d74bdc8add2315b7fd124ecc to before def5b7b2643ebba696fc60ddf675dca13f073486Affected
LinuxLinux	5.15Affected before 5.15Not affected 6.1.149 through 6.1.Not affected 6.6.101 through 6.6.Not affected 6.12.40 through 6.12.Not affected 6.15.8 through 6.15.Not affected 6.16 and laterNot affected

Product

Versions

LinuxLinux

478d770008b03ed9d74bdc8add2315b7fd124ecc to before c476d627584b7589a134a8b48dd5c6639e4401c5Affected
478d770008b03ed9d74bdc8add2315b7fd124ecc to before 7c96d519ee15a130842a6513530b4d20acd2bfcdAffected
478d770008b03ed9d74bdc8add2315b7fd124ecc to before f81b6fbe13c7fc413b5158cdffc6a59391a2a8dbAffected
478d770008b03ed9d74bdc8add2315b7fd124ecc to before 659da22dee5ff316ba63bdaeeac7b58b5442f6c2Affected
478d770008b03ed9d74bdc8add2315b7fd124ecc to before def5b7b2643ebba696fc60ddf675dca13f073486Affected

LinuxLinux

5.15Affected
before 5.15Not affected
6.1.149 through 6.1.*Not affected
6.6.101 through 6.6.*Not affected
6.12.40 through 6.12.*Not affected
6.15.8 through 6.15.*Not affected
6.16 and laterNot affected

References

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