diff --git a/sys/net/wg/if_wg.c b/sys/net/wg/if_wg.c
--- a/sys/net/wg/if_wg.c
+++ b/sys/net/wg/if_wg.c
@@ -2286,6 +2286,10 @@
 		 * The packets have the same DLT_NULL link-layer type
 		 * (i.e., 4-byte link-layer header in host byte order).
 		 */
+		if (m->m_pkthdr.len < sizeof(uint32_t)) {
+			ret = EINVAL;
+			goto error;
+		}
 		dst->sa_family = *(mtod(m, uint32_t *));
 		m_adj(m, sizeof(uint32_t));
 	}