CVE-2019-12401: XML Bomb in Apache Solr

Solr versions prior to 5.0.0 are vulnerable to an XML resource consumption attack (a.k.a. Lol Bomb) via its 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.

Vendor Disclosure:

The vendor's disclosure and fix for this vulnerability can be found here.

Proof Of Concept:

More details and the exploitation process can be found in this PDF.