CVE-2021-27905: SSRF vulnerability with the Replication handler
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.
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Event History
Frequently Asked Questions
What is the severity of CVE-2021-27905?
The severity of CVE-2021-27905 is critical with a CVSS score of 9.8.
What is the affected software for CVE-2021-27905?
The affected software for CVE-2021-27905 is Apache Solr versions up to exclusive 8.8.2.
What is an SSRF vulnerability?
An SSRF vulnerability refers to Server-Side Request Forgery, which allows an attacker to make requests to internal or external resources on behalf of a vulnerable server.
How does the ReplicationHandler in Apache Solr contribute to the vulnerability in CVE-2021-27905?
The ReplicationHandler in Apache Solr, particularly the "masterUrl" parameter, is used in the SSRF attack vector for CVE-2021-27905, allowing replication of index data from another Solr core.
Are there any available patches or fixes for CVE-2021-27905?
Yes, upgrading to Apache Solr version 8.8.2 or later will address the vulnerability of CVE-2021-27905.