CVE-2026-63920

A flaw was found in the Linux kernel's IPv6 networking stack. An unprivileged local user could exploit a vulnerability in how IPv6 extension header lengths are handled. By manipulating these headers using nftables, an attacker can trigger an out-of-bounds read, leading to information disclosure from kernel memory.

This vulnerability is rated as Moderate severity for Red Hat Enterprise Linux because exploitation is restricted to local attackers who must construct packet-filtering rules, constraining the impact primarily to kernel memory disclosure or system crash rather than remote compromise. Although unprivileged user namespaces allow local accounts to configure nftables rules within isolated network namespaces, the flaw cannot be triggered directly by untrusted incoming traffic across external network boundaries. Consequently, typical production environments face confined risk limited to local information leakage.

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.