H2O is vulnerable to stored XSS vulnerability which can lead to a Local File Include attack.

An attacker is able to gain remote code execution on a server hosting the H2O dashboard through it's POJO model import feature.

H2O included a reference to an S3 bucket that no longer existed allowing an attacker to take over the S3 bucket URL.

A Local File Inclusion (LFI) vulnerability exists in the h2o-3 REST API, allowing unauthenticated remote attackers to read arbitrary files on the server with the permissions of the user running the h2o-3 instance. This issue affects the default installation and does not require user interaction. The vulnerability can be exploited by making specific GET or POST requests to the ImportFiles and ParseSetup endpoints, respectively. This issue was identified in version 3.40.0.4 of h2o-3.

External Control of File Name or Path in h2oai/h2o-3

A vulnerability in the `/3/Parse` endpoint of h2oai/h2o-3 version 3.46.0.1 allows for a denial of service (DoS) attack. The endpoint uses a user-specified string to construct a regular expression, which is then applied to another user-specified string. By sending multiple simultaneous requests, an attacker can exhaust all available threads, leading to a complete denial of service.

A vulnerability in the `/3/ParseSetup` endpoint of h2oai/h2o-3 version 3.46.0.1 allows for a denial of service (DoS) attack. The endpoint applies a user-specified regular expression to a user-controllable string. This can be exploited by an attacker to cause inefficient regular expression complexity, leading to the exhaustion of server resources and making the server unresponsive.

A vulnerability in the h2oai/h2o-3 REST API versions 3.46.0.4 allows unauthenticated remote attackers to execute arbitrary code via deserialization of untrusted data. The vulnerability exists in the endpoints POST /99/ImportSQLTable and POST /3/SaveToHiveTable, where user-controlled JDBC URLs are passed to DriverManager.getConnection, leading to deserialization if a MySQL or PostgreSQL driver is available in the classpath. This issue is fixed in version 3.47.0.

In h2oai/h2o-3 version 3.46.0.1, the `run_tool` command exposes classes in the `water.tools` package through the `ast` parser. This includes the `XGBoostLibExtractTool` class, which can be exploited to shut down the server and write large files to arbitrary directories, leading to a denial of service.

An S3 bucket takeover vulnerability was identified in the h2oai/h2o-3 repository. The issue involves the S3 bucket 'http://s3.amazonaws.com/h2o-training', which was found to be vulnerable to unauthorized takeover.

H2O.ai H2O through 3.46.0.4 allows attackers to arbitrarily set the JDBC URL, leading to deserialization attacks, file reads, and command execution. Exploitation can occur when an attacker has access to post to the ImportSQLTable URI with a JSON document containing a connection_url property with any typical JDBC Connection URL attack payload such as one that uses queryInterceptors.

In h2oai/h2o-3 version 3.40.0.4, an exposure of sensitive information vulnerability exists due to an arbitrary system path lookup feature. This vulnerability allows any remote user to view full paths in the entire file system where h2o-3 is hosted. Specifically, the issue resides in the Typeahead API call, which when requested with a typeahead lookup of '/', exposes the root filesystem including directories such as /home, /usr, /bin, among others. This vulnerability could allow attackers to explore the entire filesystem, and when combined with a Local File Inclusion (LFI) vulnerability, could make exploitation of the server trivial.

In h2oai/h2o-3 version 3.46.0, the `run_tool` command in the `rapids` component allows the `main` function of any class under the `water.tools` namespace to be called. One such class, `MojoConvertTool`, crashes the server when invoked with an invalid argument, causing a denial of service.

In h2oai/h2o-3 version 3.46.0, the endpoint for exporting models does not restrict the export location, allowing an attacker to export a model to any file in the server's file structure, thereby overwriting it. This vulnerability can be exploited to overwrite any file on the target server with a trained model file, although the content of the overwrite is not controllable by the attacker.

In h2oai/h2o-3 version 3.46.0, an endpoint exposing a custom EncryptionTool allows an attacker to encrypt any files on the target server with a key of their choosing. The chosen key can also be overwritten, resulting in ransomware-like behavior. This vulnerability makes it possible for an attacker to encrypt arbitrary files with keys of their choice, making it exceedingly difficult for the target to recover the keys needed for decryption.

A vulnerability in the `/3/ImportFiles` endpoint of h2oai/h2o-3 version 3.46.1 allows an attacker to cause a denial of service. The endpoint takes a single GET parameter, `path`, which can be recursively set to reference itself. This leads the server to repeatedly call its own endpoint, eventually filling up the request queue and leaving the server unable to handle other requests.

A vulnerability in the typeahead endpoint of h2oai/h2o-3 version 3.46.0 allows for a denial of service. The endpoint performs a `HEAD` request to verify the existence of a specified resource without setting a timeout. An attacker can exploit this by sending multiple requests to an attacker-controlled server that hangs, causing the application to block and become unresponsive to other requests.

In h2oai/h2o-3 version 3.46.0, the `/99/Models/{name}/json` endpoint allows for arbitrary file overwrite on the target server. The vulnerability arises from the `exportModelDetails` function in `ModelsHandler.java`, where the user-controllable `mexport.dir` parameter is used to specify the file path for writing model details. This can lead to overwriting files at arbitrary locations on the host system.

A flaw has been found in h2oai h2o-3 up to 3.46.08. The impacted element is an unknown function of the file /99/ImportSQLTable of the component IBMDB2 JDBC Driver. This manipulation of the argument connection_url causes deserialization. The attack may be initiated remotely. The exploit has been published and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

A vulnerability has been found in h2oai h2o-3 up to 3.46.08. This affects an unknown function of the file /99/ImportSQLTable of the component H2 JDBC Driver. Such manipulation of the argument connection_url leads to deserialization. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Quicly, an IETF QUIC protocol implementation, is susceptible to a denial-of-service attack prior to commit d9d3df6a8530a102b57d840e39b0311ce5c9e14e. A remote attacker can exploit these bugs to trigger an assertion failure that crashes process using Quicly. Commit d9d3df6a8530a102b57d840e39b0311ce5c9e14e fixes the issue.

A deserialization vulnerability exists in h2oai/h2o-3 versions <= 3.46.0.8, allowing attackers to read arbitrary system files and execute arbitrary code. The vulnerability arises from improper handling of JDBC connection parameters, which can be exploited by bypassing regular expression checks and using double URL encoding. This issue impacts all users of the affected versions.