Collected research

Funky chunks: abusing ambiguous chunk line terminators for request smuggling

Jeppe Bonde Weikop · w4ke.info · 18 June 2025

HTTP implementations disagree over what ends a line in a chunked body: some read a bare newline inside a chunk extension as a terminator, others swallow it, and some accept any two bytes after an oversized chunk body. Pairing a proxy and server with complementary leniencies desynchronises them and smuggles a request past front-end controls.

Record

Researcher

Jeppe Bonde Weikop

Published by

w4ke.info

Date

18 June 2025

Topic

HTTP

In the archive

• Collected in the 2025 research round

Related sources

• Earlier TERM.EXT research Repository
• Smugchunks scanner

Tags

• request-smuggling
• parser-differential
• desync
• http
• reverse-proxy
• load-balancer
• filter-bypass
• cve
• tooling
• owasp-a05-2021

This page is the archive's own catalogue record. The research is the work of Jeppe Bonde Weikop, first published at the original source. Preserved copies are kept so the citation survives its host; this one was last captured on 9 August 2026.