Known Vulnerabilities
CVE-2021-29943
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.
CVE-2021-29262
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.
CVE-2021-27905
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.