CVE-2014-8150

What it actually does

CRLF injection in libcurl when using an HTTP proxy allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via CRLF sequences in a URL.

Why it matters to the business

Attackers can manipulate HTTP responses to bypass security controls, perform cache poisoning, or redirect users, leading to potential data exposure or unauthorized access across systems relying on the affected library.

How an attack unfolds

An attacker crafts a malicious URL containing CRLF sequences and supplies it to an application using libcurl with an HTTP proxy; the proxy processes the injected headers, enabling response splitting or header manipulation that the attacker leverages to interfere with subsequent requests or responses.

How to fix it

Upgrade libcurl to version 7.40.0 or later across all affected products and rebuild dependent applications; disable HTTP proxy usage where feasible until patched.

How to confirm the fix worked

Verify libcurl version is 7.40.0 or newer in package managers or build configurations; test proxy interactions with crafted URLs containing CRLF to confirm header injection is rejected.

Typical attack path

1. Identify an application or service using vulnerable libcurl with HTTP proxy support
2. Craft a URL containing CRLF sequences to inject arbitrary headers
3. Supply the URL through the affected client or proxy interaction
4. Exploit the split response to perform cache poisoning, header manipulation, or redirect attacks

How to detect it

Review application and proxy logs for URLs containing encoded CRLF sequences (%0D%0A or \r\n) originating from untrusted sources; inspect network traffic for unexpected HTTP headers in responses from proxied connections.

• %0D%0A in URL parameters
• \r\n sequences in logged HTTP requests to proxies
• Unexpected Set-Cookie or Location headers in proxied responses

What your security team should do

• Prioritize patching libcurl in all environments due to widespread use in network clients
• Audit applications for proxy usage and restrict untrusted URL inputs
• Monitor for updates in Debian and Ubuntu distributions and apply as available