2018 CN2

 is a very small asteroid, classified as a near-Earth object of the Apollo group, approximately 5 to 16 meters in diameter. It was first observed by astronomers of the Mount Lemmon Survey at Mount Lemmon Observatory, Arizona, on 8 February 2018, one day prior its close encounter with Earth at 0.18 lunar distances.

Orbit and classification
is a member of the Apollo asteroids, which cross the orbit of Earth. Apollo's are the largest group of near-Earth objects with nearly 10 thousand known objects.

Based on a high orbital uncertainty, this asteroid orbits the Sun at a distance of 0.63–1.77 AU once every 16 months (482 days; semi-major axis of 1.20 AU). Its orbit has an eccentricity of 0.47 and an inclination of 26° with respect to the ecliptic. With an aphelion of 1.77 AU, it is also a Mars-crosser, as it crosses the orbit of the Red Planet at 1.666 AU. The body's observation arc begins at Mount Lemmon with its first observation on 8 February 2018.

Close encounters
The object has an exceptionally low minimum orbital intersection distance with Earth of 0.000077 AU, or 0.03 lunar distances (LD).

2018 flyby
On 9 February 2018, passed at a nominal distance of only 0.000466964 AU from Earth at 7:25 UTC. This corresponds to 0.18 LD. Based on the body's high orbital uncertainty, all subsequent close encounters in 2022, 2023, 2026, 2027 and 2031, are projected to occur at a distance of more than 15 million kilometers (0.1 AU; 39 LD).

Physical characteristics
The Minor Planet Center estimates a diameter of 5–16 meters. Based on a generic magnitude-to-diameter conversion, measures between 9 and 17 meters in diameter, for an absolute magnitude of 27.653, and an assumed albedo between 0.057 and 0.20, which represent typical values for carbonaceous and stony asteroids, respectively.

As of 2018, no rotational lightcurve of has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.

Numbering and naming
This minor planet has neither been numbered nor named.