Language: TypeScript
Label: safe
CWE: CWE-918 \u2014 Server-Side Request Forgery (SSRF)
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

Code:
module.exports = async (ctx) => {
    const { column } = ctx.params;
    if (!isValidHost(column)) {
        throw Error('Invalid column');
    }
    const link = `http://${column}.blog.caixin.com`;
    const feed_url = `${link}/feed`;
    const feed = await parser.parseURL(feed_url);

    const title = `财新博客 - ${/[^»]*$/.exec(feed.title)[0]}`;

    const items = await Promise.all(
        feed.items.slice(0, 10).map(async (item, index) => {
            const link = item.link;
            const single = {
                title: item.title,
                pubDate: item.pubDate,
                link,
                author: item['dc:creator'],
            };
            const other = await ctx.cache.tryGet(link, () => load(link, index === 0));
            return Promise.resolve(Object.assign({}, single, other));
        })
    );

    ctx.state.data = {
        title,
        link,
        description: items[0].feed_description,
        item: items,
    };
};