Executive Summary
CVE-2026-98432 is a critical use-after-free (UAF) vulnerability in the Linux kernel's TCP stack, specifically within the `tcp_v4_syn_recv_sock` function. The flaw is triggered by incoming IPv4 SYN packets containing IP options, such as Record Route or Timestamp, during the handshake process. While primarily resulting in kernel crashes or reboots, specific configurations involving MPTCP listeners have been identified as potential paths for root-level exploitation.
Technical analysis indicates the bug dates back to kernel version 4.4, affecting a wide range of unpatched Linux distributions. Attackers can weaponize the race condition to cause slab corruption or general protection faults. Defenders should prioritize patching internet-facing systems and monitoring for unexpected reboots or specific kernel oops signatures related to the TCP handshake path.
Failure to address this vulnerability poses a significant risk of service disruption via Denial of Service (DoS) and potential system compromise. Organizations unable to patch immediately should consider interim mitigations such as dropping TCP packets with IP options and disabling MPTCP where not required.
Key Details
Threat Name
CVE-2026-98432
Affects
Linux kernel
Adversary
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MITRE Techniques
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Malware/Tools
None identified