Solr uses a PKI based mechanism to secure inter-node communication
when security is enabled. It is possible to fake it by cleverly
constructing a node name that does not exist and pointing to the
attackers machine. This means, the system is only as secure as an
unprotected Solr while the user believes it is secure.
who is affected?
This feature was introduced in
SOLR-7849 (Solr 5.3). So, every release
after 5.3 is vulnerable if they use this feature. Systems using
BasicAuth are affected and any custom authentication implementations
using this feature may also be vulnerable. However, Kerberos users are
What is the fix?
The fix includes checking if the node name is actually a member of the