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.

Summary

Log4j versions prior to 2.16.0 are subject to a remote code execution vulnerability via the ldap JNDI parser. As per Apache's Log4j security guide: Apache Log4j2 <=2.14.1 JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.16.0, this behavior has been disabled by default.

Log4j version 2.15.0 contained an earlier fix for the vulnerability, but that patch did not disable attacker-controlled JNDI lookups in all situations. For more information, see the Updated advice for version 2.16.0 section of this advisory.

Impact

Logging untrusted or user controlled data with a vulnerable version of Log4J may result in Remote Code Execution (RCE) against your application. This includes untrusted data included in logged errors such as exception traces, authentication failures, and other unexpected vectors of user controlled input.

Affected versions

Any Log4J version prior to v2.15.0 is affected to this specific issue.

The v1 branch of Log4J which is considered End Of Life (EOL) is vulnerable to other RCE vectors so the recommendation is to still update to 2.16.0 where possible.

Security releases Additional backports of this fix have been made available in versions 2.3.1, 2.12.2, and 2.12.3

Affected packages Only the org.apache.logging.log4j:log4j-core package is directly affected by this vulnerability. The org.apache.logging.log4j:log4j-api should be kept at the same version as the org.apache.logging.log4j:log4j-core package to ensure compatability if in use.

Remediation Advice

Updated advice for version 2.16.0

The Apache Logging Services team provided updated mitigation advice upon the release of version 2.16.0, which disables JNDI by default and completely removes support for message lookups. Even in version 2.15.0, lookups used in layouts to provide specific pieces of context information will still recursively resolve, possibly triggering JNDI lookups. This problem is being tracked as CVE-2021-45046. More information is available on the GitHub Security Advisory for CVE-2021-45046.

Users who want to avoid attacker-controlled JNDI lookups but cannot upgrade to 2.16.0 must ensure that no such lookups resolve to attacker-provided data and ensure that the the JndiLookup class is not loaded.

Please note that Log4J v1 is End Of Life (EOL) and will not receive patches for this issue. Log4J v1 is also vulnerable to other RCE vectors and we recommend you migrate to Log4J 2.16.0 where possible.

Apache Tomcat contains a path equivalence vulnerability that allows a remote attacker to execute code, disclose information, or inject malicious content via a partial PUT request. This vulnerability can be chained with CVE‑2026‑34486.

A deserialization flaw was found in Apache log4j 1.2.x. While reading serialized log events, they are improperly deserialized.

Note this is the same as CVE-2020-9493 which identified a deserialization issue in Apache Chainsaw. Prior to Chainsaw V2.0, Chainsaw was a component of Apache Log4j 1.2.x.

References:

https://www.openwall.com/lists/oss-security/2022/01/18/5

A flaw was found in the Java logging library Apache Log4j in version 1.x. JDBCAppender in Log4j 1.x is vulnerable to SQL injection in untrusted data. This allows a remote attacker to run SQL statements in the database if the deployed application is configured to use JDBCAppender with certain interpolation tokens.

A flaw was found in the Java logging library Apache Log4j in version 1.x. JMSSink in Log4j 1.x is vulnerable to deserialization of untrusted data. This allows a remote attacker to execute code on the server if JMSSink is deployed and has been configured to perform JNDI requests.

The RocketMQ NameServer component still has a remote command execution vulnerability as the CVE-2023-33246 issue was not completely fixed in version 5.1.1.

When NameServer address are leaked on the extranet and lack permission verification, an attacker can exploit this vulnerability by using the update configuration function on the NameServer component to execute commands as the system users that RocketMQ is running as.

It is recommended for users to upgrade their NameServer version to 5.1.2 or above for RocketMQ 5.x or 4.9.7 or above for RocketMQ 4.x to prevent these attacks.

For RocketMQ versions 5.1.0 and below, under certain conditions, there is a risk of remote command execution.

Several components of RocketMQ, including NameServer, Broker, and Controller, are leaked on the extranet and lack permission verification, an attacker can exploit this vulnerability by using the update configuration function to execute commands as the system users that RocketMQ is running as. Additionally, an attacker can achieve the same effect by forging the RocketMQ protocol content.

To prevent these attacks, users are recommended to upgrade to version 5.1.1 or above for using RocketMQ 5.x or 4.9.6 or above for using RocketMQ 4.x .

Apache Log4j <=2.14.1 JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled (CVE-2021-44228).

Pre-auth RCE in Apache Ofbiz 18.12.09.

It's due to XML-RPC no longer maintained still present. This issue affects Apache OFBiz: before 18.12.10.  Users are recommended to upgrade to version 18.12.10

The vulnerability permits attackers to circumvent authentication processes, enabling them to remotely execute arbitrary code