XML External Entity (XXE) Injection Affecting org.apache.solr:solr-core package, versions [,6.6.5)[7.0.0,7.4.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published19 Jul 2018
- disclosed5 Jul 2018
- creditUnknown
Introduced: 5 Jul 2018
CVE-2018-8026 (opens in a new tab)How to fix?
Upgrade org.apache.solr:solr-core to versions 6.6.5, 7.4 or higher.
Overview
org.apache.solr:solr-core is an enterprise search platform written using Apache Lucene.
Affected versions of this package are vulnerable to XML External Entity (XXE) Injection. It can be used as XXE using the file/ftp/http protocols in order to read arbitrary local files from the server or the internal network. The manipulated files can be uploaded as config sets using solr's API, allowing to exploit that vulnerability.
Details
XXE Injection is a type of attack against an application that parses XML input. XML is a markup language that defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. By default, many XML processors allow specification of an external entity, a URI that is dereferenced and evaluated during XML processing. When an XML document is being parsed, the parser can make a request and include the content at the specified URI inside of the XML document.
Attacks can include disclosing local files, which may contain sensitive data such as passwords or private user data, using file: schemes or relative paths in the system identifier.
For example, below is a sample XML document, containing an XML element- username.
<?xml version="1.0" encoding="ISO-8859-1"?>
<username>John</username>
</xml>
An external XML entity - xxe, is defined using a system identifier and present within a DOCTYPE header. These entities can access local or remote content. For example the below code contains an external XML entity that would fetch the content of /etc/passwd and display it to the user rendered by username.
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE foo [
<!ENTITY xxe SYSTEM "file:///etc/passwd" >]>
<username>&xxe;</username>
</xml>
Other XXE Injection attacks can access local resources that may not stop returning data, possibly impacting application availability and leading to Denial of Service.