static void append_ascii_stats(const char *key, const uint16_t klen,
                               const char *val, const uint32_t vlen,
                               conn *c) {
    char *pos = c->stats.buffer + c->stats.offset;
    uint32_t nbytes = 0;
    int remaining = c->stats.size - c->stats.offset;
    int room = remaining - 1;

    if (klen == 0 && vlen == 0) {
        nbytes = snprintf(pos, room, "END\r\n");
    } else if (vlen == 0) {
        nbytes = snprintf(pos, room, "STAT %s\r\n", key);
    } else {
        nbytes = snprintf(pos, room, "STAT %s %s\r\n", key, val);
    }

    c->stats.offset += nbytes;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.