Versions of http-proxy prior to 1.18.1 are vulnerable to Denial of Service. An HTTP request with a long body triggers an ERR_HTTP_HEADERS_SENT unhandled exception that crashes the proxy server. This is only possible when the proxy server sets headers in the proxy request using the proxyReq.setHeader function.

For a proxy server running on http://localhost:3000, the following curl request triggers the unhandled exception:
curl -XPOST http://localhost:3000 -d "$(python -c 'print("x"*1025)')"

Recommendation

Upgrade to version 1.18.1 or later

References

• https://github.com/http-party/node-http-proxy/pull/1447/files
• https://www.npmjs.com/advisories/1486
• http-party/node-http-proxy@4718119