Linux Kernel EUVD-2026-27608

Update to patched kernel versions immediately: 6.6.136+ for LTS 6.6.x series, 6.12.83+ for 6.12.x series, 6.18.24+ for 6.18.x series, 6.19.14+ for 6.19.x series, or 7.0+ for mainline. Downstream distribution kernels (RHEL, Ubuntu, SUSE, Debian) will incorporate fixes in upcoming security updates - monitor vendor security advisories and apply via standard package management. Reference upstream commits at https://git.kernel.org/stable/c/5b9911582d441f72fe6ccb15ffe3303bbc07f6f5 and related branch-specific commits. For systems requiring temporary mitigation before patching, load the IPv6 kernel module (modprobe ipv6) to prevent ERR_PTR return condition - this workaround changes system behavior by enabling IPv6 stack, may conflict with security policies requiring IPv6 disabled, and should only be temporary until patching. Alternatively, block incoming ICMP Extended probe messages (Type 42) at network perimeter firewalls using iptables rule 'iptables -A INPUT -p icmp --icmp-type 42 -j DROP' - this prevents legitimate RFC 8335 diagnostics, breaks ICMP-based network troubleshooting features, and requires firewall rule deployment across infrastructure. No application-layer mitigations exist as vulnerability resides in kernel network stack. Reboot required after kernel update to activate patched code.