Apache Solr

Core creation allows users to replace "trusted" configset files with arbitrary configuration

Solr instances that (1) use the "FileSystemConfigSetService" component (the default in "standalone" or "user-managed" mode), and (2) are running without authentication and authorization are vulnerable to a sort of privilege escalation wherein individual "trusted" configset files can be ignored in favor of potentially-untrusted replacements available elsewhere on the filesystem. These replacement config files are treated as "trusted" and can use "" tags to add to Solr's classpath, which an attacker might use to load malicious code as a searchComponent or other plugin.

This issue affects all Apache Solr versions up through Solr 9.7. Users can protect against the vulnerability by enabling authentication and authorization on their Solr clusters or switching to SolrCloud (and away from "FileSystemConfigSetService"). Users are also recommended to upgrade to Solr 9.8.0, which mitigates this issue by disabling use of "" tags by default.

Relative Path Traversal vulnerability in Apache Solr.

Solr instances running on Windows are vulnerable to arbitrary filepath write-access, due to a lack of input-sanitation in the "configset upload" API. Commonly known as a "zipslip", maliciously constructed ZIP files can use relative filepaths to write data to unanticipated parts of the filesystem.  This issue affects Apache Solr: from 6.6 through 9.7.0.

Users are recommended to upgrade to version 9.8.0, which fixes the issue. Users unable to upgrade may also safely prevent the issue by using Solr's "Rule-Based Authentication Plugin" to restrict access to the configset upload API, so that it can only be accessed by a trusted set of administrators/users.

Insecure Default Initialization of Resource vulnerability in Apache Solr.

New ConfigSets that are created via a Restore command, which copy a configSet from the backup and give it a new name, are created without setting the "trusted" metadata. ConfigSets that do not contain the flag are trusted implicitly if the metadata is missing, therefore this leads to "trusted" ConfigSets that may not have been created with an Authenticated request. "trusted" ConfigSets are able to load custom code into classloaders, therefore the flag is supposed to only be set when the request that uploads the ConfigSet is Authenticated & Authorized.

This issue affects Apache Solr: from 6.6.0 before 8.11.4, from 9.0.0 before 9.7.0. This issue does not affect Solr instances that are secured via Authentication/Authorization.

Users are primarily recommended to use Authentication and Authorization when running Solr. However, upgrading to version 9.7.0, or 8.11.4 will mitigate this issue otherwise.

Improper Authentication vulnerability in Apache Solr.

Solr instances using the PKIAuthenticationPlugin, which is enabled by default when Solr Authentication is used, are vulnerable to Authentication bypass. A fake ending at the end of any Solr API URL path, will allow requests to skip Authentication while maintaining the API contract with the original URL Path. This fake ending looks like an unprotected API path, however it is stripped off internally after authentication but before API routing.

This issue affects Apache Solr: from 5.3.0 before 8.11.4, from 9.0.0 before 9.7.0.

Users are recommended to upgrade to version 9.7.0, or 8.11.4, which fix the issue.

Improper Control of Dynamically-Managed Code Resources, Unrestricted Upload of File with Dangerous Type, Inclusion of Functionality from Untrusted Control Sphere vulnerability in Apache Solr.This issue affects Apache Solr: from 6.0.0 through 8.11.2, from 9.0.0 before 9.4.1.

In the affected versions, Solr ConfigSets accepted Java jar and class files to be uploaded through the ConfigSets API. When backing up Solr Collections, these configSet files would be saved to disk when using the LocalFileSystemRepository (the default for backups). If the backup was saved to a directory that Solr uses in its ClassPath/ClassLoaders, then the jar and class files would be available to use with any ConfigSet, trusted or untrusted.

When Solr is run in a secure way (Authorization enabled), as is strongly suggested, this vulnerability is limited to extending the Backup permissions with the ability to add libraries. Users are recommended to upgrade to version 8.11.3 or 9.4.1, which fix the issue. In these versions, the following protections have been added:

* Users are no longer able to upload files to a configSet that could be executed via a Java ClassLoader.
* The Backup API restricts saving backups to directories that are used in the ClassLoader.

Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Apache Solr.This issue affects Apache Solr: from 6.0.0 through 8.11.2, from 9.0.0 before 9.4.1.

Solr Streaming Expressions allows users to extract data from other Solr Clouds, using a "zkHost" parameter. When original SolrCloud is setup to use ZooKeeper credentials and ACLs, they will be sent to whatever "zkHost" the user provides. An attacker could setup a server to mock ZooKeeper, that accepts ZooKeeper requests with credentials and ACLs and extracts the sensitive information, then send a streaming expression using the mock server's address in "zkHost". Streaming Expressions are exposed via the "/streaming" handler, with "read" permissions.

Users are recommended to upgrade to version 8.11.3 or 9.4.1, which fix the issue. From these versions on, only zkHost values that have the same server address (regardless of chroot), will use the given ZooKeeper credentials and ACLs when connecting.

Incorrect Permission Assignment for Critical Resource, Improper Control of Dynamically-Managed Code Resources vulnerability in Apache Solr.

This issue affects Apache Solr: from 8.10.0 through 8.11.2, from 9.0.0 before 9.3.0.

The Schema Designer was introduced to allow users to more easily configure and test new Schemas and configSets. However, when the feature was created, the "trust" (authentication) of these configSets was not considered. External library loading is only available to configSets that are "trusted" (created by authenticated users), thus non-authenticated users are unable to perform Remote Code Execution. Since the Schema Designer loaded configSets without taking their "trust" into account, configSets that were created by unauthenticated users were allowed to load external libraries when used in the Schema Designer.

Users are recommended to upgrade to version 9.3.0, which fixes the issue.

Insufficiently Protected Credentials vulnerability in Apache Solr.

This issue affects Apache Solr: from 6.0.0 through 8.11.2, from 9.0.0 before 9.3.0. One of the two endpoints that publishes the Solr process' Java system properties, /admin/info/properties, was only setup to hide system properties that had "password" contained in the name. There are a number of sensitive system properties, such as "basicauth" and "aws.secretKey" do not contain "password", thus their values were published via the "/admin/info/properties" endpoint. This endpoint populates the list of System Properties on the home screen of the Solr Admin page, making the exposed credentials visible in the UI.

This /admin/info/properties endpoint is protected under the "config-read" permission. Therefore, Solr Clouds with Authorization enabled will only be vulnerable through logged-in users that have the "config-read" permission. Users are recommended to upgrade to version 9.3.0 or 8.11.3, which fixes the issue. A single option now controls hiding Java system property for all endpoints, "-Dsolr.hiddenSysProps". By default all known sensitive properties are hidden (including "-Dbasicauth"), as well as any property with a name containing "secret" or "password".

Users who cannot upgrade can also use the following Java system property to fix the issue: Â '-Dsolr.redaction.system.pattern=.*(password|secret|basicauth).*'

Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Apache Solr. The Solr Metrics API publishes all unprotected environment variables available to each Apache Solr instance. Users are able to specify which environment variables to hide, however, the default list is designed to work for known secret Java system properties. Environment variables cannot be strictly defined in Solr, like Java system properties can be, and may be set for the entire host, unlike Java system properties which are set per-Java-proccess.

The Solr Metrics API is protected by the "metrics-read" permission. Therefore, Solr Clouds with Authorization setup will only be vulnerable via users with the "metrics-read" permission. This issue affects Apache Solr: from 9.0.0 before 9.3.0.

Users are recommended to upgrade to version 9.3.0 or later, in which environment variables are not published via the Metrics API.

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

An Improper Input Validation vulnerability in DataImportHandler of Apache Solr allows an attacker to provide a Windows UNC path resulting in an SMB network call being made from the Solr host to another host on the network. If the attacker has wider access to the network, this may lead to SMB attacks, which may result in: * The exfiltration of sensitive data such as OS user hashes (NTLM/LM hashes), * In case of misconfigured systems, SMB Relay Attacks which can lead to user impersonation on SMB Shares or, in a worse-case scenario, Remote Code Execution This issue affects all Apache Solr versions prior to 8.11.1. This issue only affects Windows.

When using ConfigurableInternodeAuthHadoopPlugin for authentication, Apache Solr versions prior to 8.8.2 would forward/proxy distributed requests using server credentials instead of original client credentials. This would result in incorrect authorization resolution on the receiving hosts.

When starting Apache Solr versions prior to 8.8.2, configured with the SaslZkACLProvider or VMParamsAllAndReadonlyDigestZkACLProvider and no existing security.json znode, if the optional read-only user is configured then Solr would not treat that node as a sensitive path and would allow it to be readable. Additionally, with any ZkACLProvider, if the security.json is already present, Solr will not automatically update the ACLs.

The ReplicationHandler (normally registered at "/replication" under a Solr core) in Apache Solr has a "masterUrl" (also "leaderUrl" alias) parameter that is used to designate another ReplicationHandler on another Solr core to replicate index data into the local core. To prevent a SSRF vulnerability, Solr ought to check these parameters against a similar configuration it uses for the "shards" parameter. Prior to this bug getting fixed, it did not. This problem affects essentially all Solr versions prior to it getting fixed in 8.8.2.

Apache Solr versions 6.6.0 to 6.6.6, 7.0.0 to 7.7.3 and 8.0.0 to 8.6.2 prevents some features considered dangerous (which could be used for remote code execution) to be configured in a ConfigSet that's uploaded via API without authentication/authorization. The checks in place to prevent such features can be circumvented by using a combination of UPLOAD/CREATE actions.

Reported in SOLR-14515 (private) and fixed in SOLR-14561 (public), released in Solr version 8.6.0. The Replication handler (https://lucene.apache.org/solr/guide/8_6/index-replication.html#http-api-commands-for-the-replicationhandler) allows commands backup, restore and deleteBackup. Each of these take a location parameter, which was not validated, i.e you could read/write to any location the solr user can access.

In Apache Solr, the cluster can be partitioned into multiple collections and only a subset of nodes actually host any given collection. However, if a node receives a request for a collection it does not host, it proxies the request to a relevant node and serves the request. Solr bypasses all authorization settings for such requests. This affects all Solr versions prior to 7.7 that use the default authorization mechanism of Solr (RuleBasedAuthorizationPlugin).

Apache Solr 5.0.0 to Apache Solr 8.3.1 are vulnerable to a Remote Code Execution through the VelocityResponseWriter. A Velocity template can be provided through Velocity templates in a configset `velocity/` directory or as a parameter. A user defined configset could contain renderable, potentially malicious, templates. Parameter provided templates are disabled by default, but can be enabled by setting `params.resource.loader.enabled` by defining a response writer with that setting set to `true`. Defining a response writer requires configuration API access. Solr 8.4 removed the params resource loader entirely, and only enables the configset-provided template rendering when the configset is `trusted` (has been uploaded by an authenticated user).

Solr versions 1.3.0 to 1.4.1, 3.1.0 to 3.6.2 and 4.0.0 to 4.10.4 are vulnerable to an XML resource consumption attack (a.k.a. Lol Bomb) via it’s update handler.?By leveraging XML DOCTYPE and ENTITY type elements, the attacker can create a pattern that will expand when the server parses the XML causing OOMs.

In Apache Solr, the DataImportHandler, an optional but popular module to pull in data from databases and other sources, has a feature in which the whole DIH configuration can come from a request's "dataConfig" parameter. The debug mode of the DIH admin screen uses this to allow convenient debugging / development of a DIH config. Since a DIH config can contain scripts, this parameter is a security risk. Starting with version 8.2.0 of Solr, use of this parameter requires setting the Java System property "enable.dih.dataConfigParam" to true.

Server Side Request Forgery in Apache Solr, versions 1.3 until 7.6 (inclusive). Since the "shards" parameter does not have a corresponding whitelist mechanism, a remote attacker with access to the server could make Solr perform an HTTP GET request to any reachable URL.

In Apache Solr versions 5.0.0 to 5.5.5 and 6.0.0 to 6.6.5, the Config API allows to configure the JMX server via an HTTP POST request. By pointing it to a malicious RMI server, an attacker could take advantage of Solr's unsafe deserialization to trigger remote code execution on the Solr side.

This vulnerability in Apache Solr 6.0.0 to 6.6.4 and 7.0.0 to 7.3.1 relates to an XML external entity expansion (XXE) in Solr config files (currency.xml, enumsConfig.xml referred from schema.xml, TIKA parsecontext config file). In addition, Xinclude functionality provided in these config files is also affected in a similar way. The vulnerability can be used as XXE using file/ftp/http protocols in order to read arbitrary local files from the Solr server or the internal network. The manipulated files can be uploaded as configsets using Solr's API, allowing to exploit that vulnerability.

This vulnerability in Apache Solr 6.0.0 to 6.6.3, 7.0.0 to 7.3.0 relates to an XML external entity expansion (XXE) in Solr config files (solrconfig.xml, schema.xml, managed-schema). In addition, Xinclude functionality provided in these config files is also affected in a similar way. The vulnerability can be used as XXE using file/ftp/http protocols in order to read arbitrary local files from the Solr server or the internal network. Users are advised to upgrade to either Solr 6.6.4 or Solr 7.3.1 releases both of which address the vulnerability. Once upgrade is complete, no other steps are required. Those releases only allow external entities and Xincludes that refer to local files / zookeeper resources below the Solr instance directory (using Solr's ResourceLoader); usage of absolute URLs is denied. Keep in mind, that external entities and XInclude are explicitly supported to better structure config files in large installations. Before Solr 6 this was no problem, as config files were not accessible through the APIs.

This vulnerability in Apache Solr 1.2 to 6.6.2 and 7.0.0 to 7.2.1 relates to an XML external entity expansion (XXE) in the `&dataConfig=` parameter of Solr's DataImportHandler. It can be used as XXE using file/ftp/http protocols in order to read arbitrary local files from the Solr server or the internal network.