SECURITY ALERT

Update 08/13/2025

Alerted Vulnerabilities

A mismatch caused by client-triggered server-sent stream resets between HTTP/2 specifications and the internal architectures of some HTTP/2 implementations may result in excessive server resource consumption leading to denial-of-service (DoS). This vulnerability is tracked as CVE-2025-8671 and is known colloquially as "MadeYouReset." This vulnerability is similar to CVE-2023-44487, colloquially known as "Rapid Reset", which abused client-sent stream resets. HTTP/2 introduced stream cancellation - the ability of both client and server to immediately close a stream at any time. However, after a stream is canceled, many implementations keep processing the request, compute the response, but don't send it back to the client. This creates a mismatch between the amount of active streams from the HTTP/2 point of view, and the actual active HTTP requests the backend server is processing.

By opening streams and then rapidly triggering the server to reset them using malformed frames or flow control errors, an attacker can exploit a discrepancy created between HTTP/2 streams accounting, and the servers active HTTP requests. Streams reset by the server are considered closed, even though backend processing continues. This allows a client to cause the server to handle an unbounded number of concurrent HTTP/2 requests on a single connection.

The flaw largely stems from many implementations of the HTTP/2 protocol equating resetting streams to closing them; however, in practice, the server will still process them. An attacker can exploit this to continually send reset requests, where the protocol is considering these reset streams as closed, but the server will still be processing them, causing a DoS.

CVE-2025-8671

A mismatch caused by client-triggered server-sent stream resets between HTTP/2 specifications and the internal architectures of some HTTP/2 implementations may result in excessive server resource consumption leading to denial-of-service (DoS). By opening streams and then rapidly triggering the server to reset them—using malformed frames or flow control errors—an attacker can exploit incorrect stream accounting. Streams reset by the server are considered closed at the protocol level, even though backend processing continues. This allows a client to cause the server to handle an unbounded number of concurrent streams on a single connection. This CVE will be updated as affected product details are released.

CVE-2025-55163

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.124.Final and 4.2.4.Final, Netty is vulnerable to MadeYouReset DDoS. This is a logical vulnerability in the HTTP/2 protocol, that uses malformed HTTP/2 control frames in order to break the max concurrent streams limit - which results in resource exhaustion and distributed denial of service. This issue has been patched in versions 4.1.124.Final and 4.2.4.Final

CVE-2025-54500

An HTTP/2 implementation flaw allows a denial-of-service (DoS) that uses malformed HTTP/2 control frames in order to break the max concurrent streams limit (HTTP/2 MadeYouReset Attack). Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVE-2025-48989

Improper Resource Shutdown or Release vulnerability in Apache Tomcat made Tomcat vulnerable to the made you reset attack. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.9, from 10.1.0-M1 through 10.1.43 and from 9.0.0.M1 through 9.0.107. Older, EOL versions may also be affected. Users are recommended to upgrade to one of versions 11.0.10, 10.1.44 or 9.0.108 which fix the issue.