In Eclipse Jetty, versions <=9.4.57, <=10.0.25, <=11.0.25, <=12.0.21, <=12.1.0.alpha2, an HTTP/2 client may trigger the server to send RST_STREAM frames, for example by sending frames that are malformed or that should not be sent in a particular stream state, therefore forcing the server to consume resources such as CPU and memory.
For example, a client can open a stream and then send WINDOW_UPDATE frames with window size increment of 0, which is illegal. Per specification https://www.rfc-editor.org/rfc/rfc9113.html#name-window_update , the server should send a RST_STREAM frame. The client can now open another stream and send another bad WINDOW_UPDATE, therefore causing the server to consume more resources than necessary, as this case does not exceed the max number of concurrent streams, yet the client is able to create an enormous amount of streams in a short period of time.
The attack can be performed with other conditions (for example, a DATA frame for a closed stream) that cause the server to send a RST_STREAM frame.
Links:
| Software | From | Fixed in |
|---|---|---|
org.eclipse.jetty.http2 / http2-common
|
9.3.0 | 9.4.58 |
org.eclipse.jetty.http2 / http2-common
|
10.0.0 | 10.0.26 |
org.eclipse.jetty.http2 / http2-common
|
11.0.0 | 11.0.26 |
org.eclipse.jetty.http2 / jetty-http2-common
|
12.0.0 | 12.0.25 |
org.eclipse.jetty.http2 / jetty-http2-common
|
12.1.0.alpha0 | 12.1.0.beta3 |
| eclipse / jetty | 9.3.0 | 9.4.57.x |
| eclipse / jetty | 10.0.0 | 10.0.25.x |
| eclipse / jetty | 11.0.0 | 11.0.25.x |
| eclipse / jetty | 12.0.0 | 12.0.21.x |
| eclipse / jetty | 12.1.0-alpha0 | 12.1.0-alpha0.x |
| eclipse / jetty | 12.1.0-alpha1 | 12.1.0-alpha1.x |
| eclipse / jetty | 12.1.0-alpha2 | 12.1.0-alpha2.x |
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
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