Improper Initialization in Linux kernel - CVE-2026-80585
Published: August 27, 2026
Vulnerability identifier: #VU145911
CSH Severity: High
CVSS v4: 8.8 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-80585
CWE-ID: CWE-665
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service and corrupt integrity.
The vulnerability exists due to improper state management in mptcp_fastopen_subflow_synack_set_params() and check_fully_established() when processing data-less TCP Fast Open SYN packets with a valid cookie. A remote attacker can send a specially crafted SYN packet to cause a denial of service and corrupt integrity.
The issue occurs when a valid-cookie SYN carries no data, leaving the receive queue empty and stale MPTFO state behind.
Affected software
Linux kernel
How to mitigate CVE-2026-80585
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
External References
- https://git.kernel.org/stable/c/72b4a0c51a4b550d40301d60a366b429b8c8e78d
- https://git.kernel.org/stable/c/75e564b2ced1cc3d9a8904c7d2d2bb448fffb8b5
- https://git.kernel.org/stable/c/e00b63056fb4f261455b3e5df5268a1f8ce47a87
- https://git.kernel.org/stable/c/f75f174edc865738522e514d042cf5627f084859
- https://git.kernel.org/stable/c/fca7e444c04689fe4cc6b56f2725f804a4bb1ef9