CVE intelligence

CVE-2026-43198

Vulnerability intelligence

Published May 6, 2026Sources checked Oct 27, 2026

9.8CRITICALCVSS out of 10

What this means

Review the available evidence

CVE-2026-43198 and is rated Critical severity with a CVSS score of 9.8. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.

What to do next

Remediation and response

Microsoft Security Response Center guidance

Vendor revision: Sep 24, 2026

Release Notes

Ubuntu Security Notices guidance

Vendor revision: Sep 22, 2026

Vendor remediation details

This update corrects flaws in the following subsystems: - x86 architecture; - InfiniBand drivers; - Network drivers; - NVME drivers; - Ext4 file system; - SMB network file system; - IPv4 networking; - Network traffic control; - TCP network protocol; - Locking primitives; - IPv6 networking; - Multipath TCP; - Netfilter; - Open vSwitch; - SCTP protocol; - SMC sockets; (CVE-2026-31414, CVE-2026-31448, CVE-2026-31705, CVE-2026-43198, CVE-2026-43378, CVE-2026-43499, CVE-2026-46266, CVE-2026-46331, CVE-2026-52924, CVE-2026-52989, CVE-2026-53086, CVE-2026-53176, CVE-2026-53212, CVE-2026-53215, CVE-2026-53224, CVE-2026-53225, CVE-2026-53228, CVE-2026-53246, CVE-2026-53359, CVE-2026-64531)

Ubuntu Security Notices guidance

Vendor revision: Sep 18, 2026

Vendor remediation details

This update corrects flaws in the following subsystems: - x86 architecture; - Cryptographic API; - InfiniBand drivers; - Media drivers; - NVIDIA Tegra memory controller driver; - Network drivers; - NVME drivers; - File systems infrastructure; - Ext4 file system; - OCFS2 file system; - IPv4 networking; - Network traffic control; - TCP network protocol; - Locking primitives; - B.A.T.M.A.N.

CISA KEVNot listedBased on the latest collected catalog

EPSS0.3%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors0Source-linked actor relationships

Overview

What is CVE-2026-43198?

In the Linux kernel, the following vulnerability has been resolved:

tcp: fix potential race in tcp_v6_syn_recv_sock()

Code in tcp_v6_syn_recv_sock() after the call to tcp_v4_syn_recv_sock() is done too late.

After tcp_v4_syn_recv_sock(), the child socket is already visible from TCP ehash table and other cpus might use it.

Since newinet->pinet6 is still pointing to the listener ipv6_pinfo bad things can happen as syzbot found.

Move the problematic code in tcp_v6_mapped_child_init() and call this new helper from tcp_v4_syn_recv_sock() before the ehash insertion.

This allows the removal of one tcp_sync_mss(), since tcp_v4_syn_recv_sock() will call it with the correct context.

Source: NVD