Red Hat Product Security issued an advisory for a kernel security update that fixes use-after-free vulnerabilities in the Linux kernel. The primary issues are CVE-2025-38248, a use-after-free in bridge multicast in the function br_multicast_port_ctx_init, and CVE-2026-23001, a possible use-after-free in macvlan_forward_source(). These vulnerabilities affect Red Hat Enterprise Linux 9.6 Extended Update Support and related CodeReady Linux Builder and BaseOS/AppStream components. The advisory references multiple CVEs but highlights these two as security fixes. The update requires installing the patched kernel packages and rebooting the system for the fix to take effect.

The vulnerabilities are use-after-free bugs in core Linux kernel networking components (bridge multicast and macvlan). Such flaws can lead to memory corruption, potentially causing system instability or enabling privilege escalation or denial of service. The advisory rates the security impact as Moderate. There are no known exploits in the wild at the time of the advisory.

Red Hat has released updated kernel packages that address these vulnerabilities. Users of affected Red Hat Enterprise Linux 9.6 Extended Update Support and related products should apply the kernel update as provided by Red Hat and reboot their systems to activate the fix. For detailed update instructions, refer to Red Hat's official guidance at https://access.redhat.com/articles/11258. No additional mitigation steps are indicated beyond applying the official update.