The Red Hat kernel security update fixes three vulnerabilities: CVE-2025-40168 involves the smc subsystem where __sk_dst_get() and dst_dev_rcu() are now used in smc_clc_prfx_match() to address the issue; CVE-2025-71085 addresses a BUG() triggered in the IPv6 code path pskb_expand_head() during calipso_skbuff_setattr(); CVE-2026-23097 resolves a denial of service vulnerability caused by a deadlock in hugetlb folio migration. These fixes are included in a kernel update for Red Hat Enterprise Linux 9 and its extended update support versions. The advisory recommends applying the update and rebooting the system to mitigate these issues.

The vulnerabilities affect the Linux kernel core, potentially causing system instability or denial of service conditions. Specifically, the deadlock in hugetlb folio migration can lead to denial of service. The IPv6 BUG() may cause kernel crashes. The smc vulnerability involves improper function usage that could lead to undefined behavior. Red Hat rates these issues as moderate in severity.

Red Hat has released an official kernel update for Red Hat Enterprise Linux 9 and related variants that addresses these vulnerabilities. Users should apply the update as detailed in the Red Hat advisory (https://access.redhat.com/articles/11258) and reboot their systems for the changes to take effect. No additional mitigation steps are indicated beyond applying the official patch.