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.

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).

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.

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=<inlinexml>` 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.

When using the Index Replication feature, Apache Solr nodes can pull index files from a master/leader node using an HTTP API which accepts a file name. However, Solr before 5.5.4 and 6.x before 6.4.1 did not validate the file name, hence it was possible to craft a special request involving path traversal, leaving any file readable to the Solr server process exposed. Solr servers protected and restricted by firewall rules and/or authentication would not be at risk since only trusted clients and users would gain direct HTTP access.

Cross-site scripting (XSS) vulnerability in webapp/web/js/scripts/plugins.js in the stats page in the Admin UI in Apache Solr before 5.3.1 allows remote attackers to inject arbitrary web script or HTML via the entry parameter to a plugins/cache URI.

Cross-site scripting (XSS) vulnerability in webapp/web/js/scripts/schema-browser.js in the Admin UI in Apache Solr before 5.3 allows remote attackers to inject arbitrary web script or HTML via a crafted schema-browse URL.

Multiple cross-site scripting (XSS) vulnerabilities in the Admin UI in Apache Solr before 5.1 allow remote attackers to inject arbitrary web script or HTML via crafted fields that are mishandled during the rendering of the (1) Analysis page, related to webapp/web/js/scripts/analysis.js or (2) Schema-Browser page, related to webapp/web/js/scripts/schema-browser.js.

Cross-site scripting (XSS) vulnerability in the Admin UI Plugin / Stats page in Apache Solr 4.x before 4.10.3 allows remote attackers to inject arbitrary web script or HTML via the fieldvaluecache object.

Directory traversal vulnerability in SolrResourceLoader in Apache Solr before 4.6 allows remote attackers to read arbitrary files via a .. (dot dot) or full pathname in the tr parameter to solr/select/, when the response writer (wt parameter) is set to XSLT. NOTE: this can be leveraged using a separate XXE (XML eXternal Entity) vulnerability to allow access to files across restricted network boundaries.