CVE-2025-38552 mptcp: plug races between subflow fail and subflow creation
A race condition in the Linux kernel MPTCP subsystem between subflow failure and creation can lead to system instability or denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-38552?
CVE-2025-38552 is a critical vulnerability in Debian Debian Linux, published on 16 Aug 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2025-38552?
It affects 2 products.
Products include Debian Debian Linux, Linux kernel.
How do I fix CVE-2025-38552?
Apply the vendor's patch.
Is CVE-2025-38552 being exploited?
There is no known exploitation of CVE-2025-38552 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as AZL-66329, BELL-CVE-2025-38552, DEBIAN-CVE-2025-38552, GHSA-h9hh-vjgw-q6wq, ROOT-OS-DEBIAN-12-CVE-2025-38552, ROOT-OS-DEBIAN-13-CVE-2025-38552 and 3 more.