CVE-2026-64298

A flaw was found in the Linux kernel's NFSv4 implementation. A local user could exploit a vulnerability where opening a file with O_TRUNC (truncate) and O_RDONLY (read-only) flags would bypass the necessary write permission checks. This oversight allows an attacker to truncate a file without having explicit write access, leading to unauthorized data modification.

This vulnerability is classified as having a Moderate severity for Red Hat Enterprise Linux because exploitation is restricted to authenticated local users on an NFSv4 client and requires specific timing where an active write delegation is already cached for the target file. Although an unprivileged account can truncate files without possessing appropriate write rights—thereby impacting data integrity and availability—the flaw cannot be exploited across the network without local access and does not enable privilege escalation or arbitrary code execution.

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.