HTTP Request Smuggling Affecting org.http4s:http4s-blaze-server_2.13 package, versions [,0.23.18)[1.0.0-M2,1.0.0-M42)
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- published26 Jul 2026
- disclosed24 Jul 2026
- creditERobertGII
Introduced: 24 Jul 2026
New CVE NOT AVAILABLE CWE-444 (opens in a new tab)How to fix?
Upgrade org.http4s:http4s-blaze-server_2.13 to version 0.23.18, 1.0.0-M42 or higher.
Overview
Affected versions of this package are vulnerable to HTTP Request Smuggling in the process that merges HTTP/1.1 chunked-body trailer fields into Request.headers. An attacker can inject arbitrary HTTP headers by sending specially crafted trailer fields, potentially bypassing header-based trust decisions such as client IP allow-lists, rate-limits, audit logging, or internal authentication enforced by upstream proxies. This may allow spoofing of client identity or unauthorized access to protected resources.
Workaround
This vulnerability can be mitigated by deploying behind a proxy that removes trailer fields or rejects requests using trailers before forwarding, and by avoiding trust decisions based on headers that rely on proxy sanitization.