Description of the patch:
This update for radvd fixes the following issue
- CVE-2026-48715: crafted ICMPv6 Router Advertisement can lead to a stack-based buffer overflow (bsc#1268641).
Changes for radvd:
- Update to version 2.21.
- feat: RFC8319 support: Increase max AdvDefaultLifetime and MaxRtrAdvInterval.
- feat: Add DHCPv6-PD preferred flag.
- fix: improve file checks for procfs knobs.
- feat: allow libc strlcpy.
- fix: make libcheck fatal if missing with --with-check.
- refactor: make drop_root_privileges reusable.
- fix: support incoming jumbo packets.
- Avoid libbsd header with libc strlcpy.