CVE-2026-69204
Description
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember HTTP/1.1 does not reject messages containing both Transfer-Encoding and Content-Length, so an intermediary and Ember can select different body framing rules. When ember-server is behind a keep-alive intermediary that forwards both headers and frames by Content-Length, an unauthenticated attacker can smuggle a second request, bypass intermediary access controls, poison caches, or cause a victim request to be joined to an attacker-controlled prefix. The shared response parser can also desynchronize an ember-client connection when a malicious or compromised upstream sends both headers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Is your site exposed to CVE-2026-69204?
Run a free security scan — no signup, results in seconds.
Weakness Type (CWE)
References
Frequently Asked Questions
What is CVE-2026-69204? +
How do I check if I'm vulnerable to CVE-2026-69204? +
Related Vulnerabilities
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in ithewei libhv allows HTTP Response Smuggling.This issue affects libhv: through …
HTTP request desynchronization in Ping Identity PingAccess, all versions prior to 8.0.1 affected allows an attacker to send specially crafted …
This vulnerability allows a high-privileged authenticated PAM user to achieve remote command execution on the affected PAM system by sending …
An HTTP Request Smuggling [CWE-444] vulnerability in the Authentication portal of WatchGuard Fireware OS allows a remote attacker to evade …
Connection desynchronization between an HTTP proxy and the model backend. The fixes were rolled out for all proxies in front …
Member Login Script 3.3 contains a client-side desynchronization vulnerability that allows attackers to manipulate HTTP request handling by exploiting Content-Length …