Denial of Service (DoS) Affecting io.undertow:undertow-core package, versions [,2.2.18) [2.3.0.Alpha1,2.3.0.Alpha2)

io.undertow:undertow-core is a Java web server based on non-blocking IO.

Affected versions of this package are vulnerable to Denial of Service (DoS) via an AJP 400 response, when EAP 7 is improperly sending two response packets, those packets have the reuse flag set even though JBoss EAP closes the connection. A failure occurs when the connection is reused after a 400 by CPING since it reads in the second SEND_HEADERS response packet instead of a CPONG.

Denial of Service (DoS) describes a family of attacks, all aimed at making a system inaccessible to its intended and legitimate users.

Unlike other vulnerabilities, DoS attacks usually do not aim at breaching security. Rather, they are focused on making websites and services unavailable to genuine users resulting in downtime.

One popular Denial of Service vulnerability is DDoS (a Distributed Denial of Service), an attack that attempts to clog network pipes to the system by generating a large volume of traffic from many machines.

When it comes to open source libraries, DoS vulnerabilities allow attackers to trigger such a crash or crippling of the service by using a flaw either in the application code or from the use of open source libraries.

Two common types of DoS vulnerabilities:

• High CPU/Memory Consumption- An attacker sending crafted requests that could cause the system to take a disproportionate amount of time to process. For example, commons-fileupload:commons-fileupload.

• Crash - An attacker sending crafted requests that could cause the system to crash. For Example, npm ws package

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