Use of Uninitialized Variable in Linux kernel - CVE-2026-89554
Published: September 12, 2026
Vulnerability identifier: #VU149244
CSH Severity: Low
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89554
CWE-ID: CWE-457
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to corrupt the path manager's id-based subflow bookkeeping.
The vulnerability exists due to use of an uninitialized local_id field in mptcp_token_join_cookie_init_state() when reconstructing MP_JOIN request sockets for fourth acknowledgments under SYN cookies. A remote attacker can send concurrent MP_JOIN SYNs to influence the stale address ID and corrupt the path manager's id-based subflow bookkeeping.
Affected software
Linux kernel
How to mitigate CVE-2026-89554
Install security update from vendor's repository.