CVE-2026-63913
kernel: netfilter: conntrack: tcp: do not force CLOSE on invalid-seq RST without direction check
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · July 19, 2026
Updated · October 13, 2026
Description
A flaw was found in the Linux kernel's netfilter conntrack TCP state machine. A remote attacker can exploit this vulnerability by sending a specially crafted sequence of TCP (Transmission Control Protocol) packets, specifically a SYN (synchronize) packet followed by an RST (reset) packet with an invalid sequence number. This improper handling of the RST packet can prematurely terminate an active Network Address Translation (NAT) entry, making connection teardown easier than intended and potentially leading to a denial of service for affected connections.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.1 · 7CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-358 · Improperly Implemented Security Check for Standard