#VU105030 Improper locking in Linux kernel - CVE-2025-21705

Vulnerability identifier: #VU105030

Vulnerability risk: Low

CVSSv4.0: 4.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2025-21705

CWE-ID: CWE-667

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor: Linux Foundation

Description

The vulnerability allows a local user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper locking within the mptcp_sendmsg_fastopen() function in net/mptcp/protocol.c. A local user can perform a denial of service (DoS) attack.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: All versions

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External links
https://git.kernel.org/stable/c/0263fb2e7b7b88075a5d86e74c4384ee4400828d
https://git.kernel.org/stable/c/619af16b3b57a3a4ee50b9a30add9ff155541e71
https://git.kernel.org/stable/c/6ec806762318a4adde0ea63342d42d0feae95079
https://git.kernel.org/stable/c/73e268b4be27b36ae68ea10755cb003f43b38884
https://git.kernel.org/stable/c/84ac44d9fed3a56440971cbd7600a02b70b5b32a

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.