title: SSRF vulnerability with the Replication handler
description: 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.
problem types: CWE-918 Server-Side Request Forgery (SSRF)
affected:
{
product: Apache Solr
vendor: Apache Software Foundation
versions:
lessThan: 8.8.2, status: affected, version: Apache Solr, versionType: custom
}
workarounds: Ensure that any access to the replication handler is purely internal to Solr.  Typically, it's only accessed externally for diagnostic/informational purposes.