SB2026082757 - Improper Initialization in Linux kernel mptcp

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Main Vulnerability Database SB2026082757

SB2026082757 - Improper Initialization in Linux kernel mptcp

Published: August 27, 2026

Security Bulletin ID SB2026082757
CSH Severity
High
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Code execution

Breakdown by Severity

High 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper Initialization (CVE-ID: CVE-2026-80585)

CWE-ID: CWE-665 - Improper Initialization

CVSSv4: 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]


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.


Remediation

Install update from vendor's website.

References