CVE-2026-64531

A flaw was found in Open vSwitch in the Linux kernel. Improper handling of oversized nested action attributes can lead to a truncated length field, which could be exploited by a local attacker to alter kernel memory. This alteration might result in the disclosure of sensitive information or a local privilege escalation (LPE).

Note that Red Hat Enterprise Linux 9.6 and layered products which include the 9.6 kernel do not contain the commits that introduced this vulnerability.

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.

Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.

If OVS is not required on a given system, unloading the openvswitch module (modprobe -r openvswitch) eliminates the attack surface entirely. For systems that require OVS but cannot patch immediately, the single most effective mitigation is disabling unprivileged user namespaces (sysctl -w user.max_user_namespaces=0), which blocks the primary path an unprivileged attacker uses to obtain CAP_NET_ADMIN and reach the vulnerable netlink interface. Standard kernel hardening (KASLR, SMEP, SMAP, kptr_restrict) is enabled by default on supported RHEL kernels and significantly increases exploitation complexity, but these controls are defense-in-depth and not a substitute for patching or removing the vulnerable module.