FRAMESHIFTER: Security Implications of HTTP/2-to-HTTP/1 Conversion Anomalies


Bahruz Jabiyev, Steven Sprecher, Anthony Gavazzi, and Tommaso Innocenti, Northeastern University; Kaan Onarlioglu, Akamai Technologies; Engin Kirda, Northeastern University


HTTP/2 adoption is rapidly climbing. However, in practice, Internet communications still rarely happen over end-to-end HTTP/2 channels. This is due to Content Delivery Networks and other reverse proxies, ubiquitous and necessary components of the Internet ecosystem, which only support HTTP/2 on the client's end, but not the forward connection to the origin server. Instead, proxy technologies predominantly rely on HTTP/2-to-HTTP/1 protocol conversion between the two legs of the connection.

We present the first systematic exploration of HTTP/2-to-HTTP/1 protocol conversion anomalies and their security implications. We develop a novel grammar-based fuzzer for HTTP/2, experiment with 12 popular reverse proxy technologies & CDNs through HTTP/2 frame sequence and content manipulation, and discover a plethora of novel web application attack vectors that lead to Request Blackholing, Denial-of-Service, Query-of-Death, and Request Smuggling attacks.

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@inproceedings {281398,
author = {Bahruz Jabiyev and Steven Sprecher and Anthony Gavazzi and Tommaso Innocenti and Kaan Onarlioglu and Engin Kirda},
title = {{FRAMESHIFTER}: Security Implications of {HTTP/2-to-HTTP/1} Conversion Anomalies},
booktitle = {31st USENIX Security Symposium (USENIX Security 22)},
year = {2022},
isbn = {978-1-939133-31-1},
address = {Boston, MA},
pages = {1061--1075},
url = {},
publisher = {USENIX Association},
month = aug,

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