VulnerabilitiesHIGH

HTTP/1.1 is Broken: A Call for Security Overhaul

PSPortSwigger BlogOct 9, 2025
HTTP/1.1HTTP/2HTTP/3cybersecuritydata breaches
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Basically, HTTP/1.1 has serious security flaws that can be exploited by hackers.

Quick Summary

New techniques reveal serious flaws in HTTP/1.1, affecting countless organizations. This outdated protocol leaves data vulnerable to attacks. Experts urge a swift transition to secure alternatives to protect sensitive information.

What Happened

At the recent Black Hat USA 2025 and DEF CON 33 conferences, a significant revelation emerged from PortSwigger's Director of Research, James Kettle. He introduced new HTTP desync techniques that expose critical vulnerabilities in the HTTP/1.1? protocol?. This announcement has sent shockwaves through the cybersecurity? community, highlighting that HTTP/1.1 is fundamentally broken and poses a serious risk to organizations worldwide.

Kettle's findings illustrate how attackers can exploit these weaknesses to carry out malicious activities, such as injecting harmful payloads or hijacking user sessions. As more companies rely on this outdated protocol? for web communications, the urgency to address these vulnerabilities has never been greater. The implications of this research are profound, as it suggests that many existing security measures may not be sufficient to protect against these new attack vectors.

Why Should You Care

If you use the internet, whether for personal or business purposes, you should be concerned about the security of HTTP/1.1?. Every time you visit a website, your data travels over this protocol?. Imagine sending a postcard with your personal information — anyone can read it! That's how insecure HTTP/1.1? can be, making it easy for hackers to intercept and exploit your data.

For businesses, the stakes are even higher. Relying on HTTP/1.1? can lead to data breaches?, loss of customer trust, and financial repercussions. If your company processes sensitive information, you can't afford to ignore these vulnerabilities. The key takeaway? It’s time to transition to more secure protocol?s to protect your data and your customers.

What's Being Done

In response to these alarming findings, cybersecurity? experts and organizations are advocating for a shift away from HTTP/1.1? to more secure alternatives like HTTP/2 and HTTP/3. These newer protocol?s offer enhanced security features that can mitigate the risks associated with HTTP desync attacks. Here’s what you should do right now:

  • Evaluate your web infrastructure to identify reliance on HTTP/1.1?.
  • Plan a transition to HTTP/2 or HTTP/3 to enhance security.
  • Stay informed about updates from cybersecurity? experts regarding the latest threats and best practices.

Experts are closely monitoring how organizations respond to these vulnerabilities and whether they will take proactive measures to upgrade their systems. The clock is ticking, and the need for action is urgent.

💡 Tap dotted terms for explanations

🔒 Pro insight: The emergence of HTTP desync techniques signals a critical need for enterprises to adopt modern protocols to mitigate evolving threats.

Original article from

PortSwigger Blog

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