HTTP/2 Rapid reset attack The HTTP/2 protocol allows clients to indicate to the server that a previous stream should be canceled by sending a RSTSTREAM frame. The protocol does not require the client and server to coordinate the cancellation in any way, the client may do it unilaterally. The client may also assume that the cancellation will take effect immediately when the server receives the RSTSTREAM frame, before any other data from that TCP connection is processed.

Abuse of this feature is called a Rapid Reset attack because it relies on the ability for an endpoint to send a RSTSTREAM frame immediately after sending a request frame, which makes the other endpoint start working and then rapidly resets the request. The request is canceled, but leaves the HTTP/2 connection open.

The HTTP/2 Rapid Reset attack built on this capability is simple: The client opens a large number of streams at once as in the standard HTTP/2 attack, but rather than waiting for a response to each request stream from the server or proxy, the client cancels each request immediately.

The ability to reset streams immediately allows each connection to have an indefinite number of requests in flight. By explicitly canceling the requests, the attacker never exceeds the limit on the number of concurrent open streams. The number of in-flight requests is no longer dependent on the round-trip time (RTT), but only on the available network bandwidth.

In a typical HTTP/2 server implementation, the server will still have to do significant amounts of work for canceled requests, such as allocating new stream data structures, parsing the query and doing header decompression, and mapping the URL to a resource. For reverse proxy implementations, the request may be proxied to the backend server before the RSTSTREAM frame is processed. The client on the other hand paid almost no costs for sending the requests. This creates an exploitable cost asymmetry between the server and the client.

Multiple software artifacts implementing HTTP/2 are affected. This advisory was originally ingested from the swift-nio-http2 repo advisory and their original conent follows.

swift-nio-http2 specific advisory swift-nio-http2 is vulnerable to a denial-of-service vulnerability in which a malicious client can create and then reset a large number of HTTP/2 streams in a short period of time. This causes swift-nio-http2 to commit to a large amount of expensive work which it then throws away, including creating entirely new Channels to serve the traffic. This can easily overwhelm an EventLoop and prevent it from making forward progress.

swift-nio-http2 1.28 contains a remediation for this issue that applies reset counter using a sliding window. This constrains the number of stream resets that may occur in a given window of time. Clients violating this limit will have their connections torn down. This allows clients to continue to cancel streams for legitimate reasons, while constraining malicious actors.

A flaw was discovered in jackson-databind in versions before 2.9.10, 2.8.11.5 and 2.6.7.3, where it would permit polymorphic deserialization of a malicious object using commons-configuration 1 and 2 JNDI classes. An attacker could use this flaw to execute arbitrary code.

A flaw was found in Quarkus where HTTP security policies are not sanitizing certain character permutations correctly when accepting requests, resulting in incorrect evaluation of permissions. This issue could allow an attacker to bypass the security policy altogether, resulting in unauthorized endpoint access and possibly a denial of service.

A flaw was found in PostgreSQL's "ALTER ... DEPENDS ON EXTENSION", where sub-commands did not perform authorization checks. An authenticated attacker could use this flaw in certain configurations to perform drop objects such as function, triggers, et al., leading to database corruption.

A flaw was found in undertow. This issue makes achieving a denial of service possible due to an unexpected handshake status updated in SslConduit, where the loop never terminates.

An issue was discovered in FasterXML jackson-databind prior to 2.7.9.4, 2.8.11.2, and 2.9.6. When Default Typing is enabled (either globally or for a specific property), the service has the Jodd-db jar (for database access for the Jodd framework) in the classpath, and an attacker can provide an LDAP service to access, it is possible to make the service execute a malicious payload.

An issue was discovered in FasterXML jackson-databind prior to 2.7.9.4, 2.8.11.2, and 2.9.6. When Default Typing is enabled (either globally or for a specific property), the service has the Oracle JDBC jar in the classpath, and an attacker can provide an LDAP service to access, it is possible to make the service execute a malicious payload.

FasterXML jackson-databind 2.x before 2.9.8 fails to block the axis2-transport-jms class from polymorphic deserialization.

References: https://github.com/FasterXML/jackson-databind/issues/2186 https://github.com/FasterXML/jackson/wiki/Jackson-Release-2.9.8

Upstream Patch: https://github.com/FasterXML/jackson-databind/commit/42912cac4753f3f718ece875e4d486f8264c2f2b

FasterXML jackson-databind 2.x before 2.9.8 fails to block the openjpa class from polymorphic deserialization.

References: https://github.com/FasterXML/jackson-databind/issues/2186 https://github.com/FasterXML/jackson/wiki/Jackson-Release-2.9.8

Upstream Patch: https://github.com/FasterXML/jackson-databind/commit/42912cac4753f3f718ece875e4d486f8264c2f2b

FasterXML jackson-databind 2.x before 2.9.8 fails to block the jboss-common-core class from polymorphic deserialization.

References: https://github.com/FasterXML/jackson-databind/issues/2186 https://github.com/FasterXML/jackson/wiki/Jackson-Release-2.9.8

Upstream Patch: https://github.com/FasterXML/jackson-databind/commit/42912cac4753f3f718ece875e4d486f8264c2f2b

A flaw was found in Hibernate ORM in versions before 5.3.18, 5.4.18 and 5.5.0.Beta1. A SQL injection in the implementation of the JPA Criteria API can permit unsanitized literals when a literal is used in the SELECT or GROUP BY parts of the query. This flaw could allow an attacker to access unauthorized information or possibly conduct further attacks.

A flaw was found in all supported versions before wildfly-elytron-1.6.8.Final-redhat-00001, where the WildFlySecurityManager checks were bypassed when using custom security managers, resulting in an improper authorization. This flaw leads to information exposure by unauthenticated access to secure resources.

A flaw was found where some utility classes in Drools core did not use proper safeguards when deserializing data. This flaw allows an authenticated attacker to construct malicious serialized objects (usually called gadgets) and achieve code execution on the server.

An XXE vulnerability was found in BPM 7.1.0 when XmlUtils class in org.jbpm.migration package is parsing crafted XML files with DocumentBuilder that is wrongly configured.

A vulnerability was found in business-central, as shipped in rhdm-7.5.1 and rhpam-7.5.1, where encoded passwords are stored in erraisecuritycontext. The encoding used for storing the passwords is Base64, not an encryption algorithm, and any recovery of these passwords could lead to user passwords being exposed.