--- a/src/libsystemd-network/dhcp6-option.c 2018-11-02 19:08:04.002213321 +0530 +++ b/src/libsystemd-network/dhcp6-option.c 2018-11-02 19:08:51.198213161 +0530 @@ -101,7 +101,7 @@ int dhcp6_option_append_ia(uint8_t **buf return -EINVAL; } - if (*buflen < len) + if (*buflen < offsetof(DHCP6Option, data) + len) return -ENOBUFS; ia_hdr = *buf;