CVE-2026-64032

A flaw was found in the Linux kernel's bridge multicast functionality. Improper management of multicast contexts when a bridge port is removed can lead to a use-after-free vulnerability. This issue could allow a local attacker to cause a system crash, resulting in a denial of service.

Red Hat has evaluated this vulnerability as having Moderate severity because exploitation requires local administrative privileges (such as CAP_NET_ADMIN) to manipulate network bridge configurations, limiting the scope of attack to privileged users or compromised environments. The issue stems from stale multicast context tracking during the removal of a bridge port when non-default per-VLAN multicast snooping options are toggled, which can trigger a kernel crash and subsequent denial of service. Standard installations do not enable these advanced bridge multicast snooping options by default, substantially reducing exposure under typical operating conditions.

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 for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.