CVE-2016-6798 XML External Entity Reference in Apache Sling

What is CVE-2016-6798?

CVE-2016-6798 is a critical vulnerability in Apache Sling, published on 19 Jul 2017. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

In the XSS Protection API module before 1.0.12 in Apache Sling, the method XSS.getValidXML() uses an insecure SAX parser to validate the input string, which allows for XXE attacks in all scripts which use this method to validate user input, potentially allowing an attacker to read sensitive data on the filesystem, perform same-site-request-forgery (SSRF), port-scanning behind the firewall or DoS the application.

Weakness: CWE-611

Which versions are affected by CVE-2016-6798?

4 open source packages ship an affected version, including org.apache.sling:org.apache.sling.xss and org.apache.sling:org.apache.sling.xss.compat. It affects 1 product.

Products include Apache Sling.

How do I fix CVE-2016-6798?

Upgrade org.apache.sling:org.apache.sling.xss to 1.0.12 or later.

Is CVE-2016-6798 being exploited?

There is no known exploitation of CVE-2016-6798 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Other vulnerabilities in Apache Sling

• CVE-2016-5394 Cross site scripting in Apache Sling Medium 6.1
• CVE-2013-4390 Apache Sling Auth Core bundle vulnerable to Open Redirection Medium 5.8

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-7g54-vgp6-jj5w.