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Overview

Affected versions of this package are vulnerable to Arbitrary Code Execution via the StringSubstitutor interpolator object. Exploiting this vulnerability is possible when untrusted data flows into the StringSubstitutor.replace() or StringSubstitutor.replaceIn() methods.

Due to the nature of these methods as ones that process application data and not user input, a remote attacker would need prior access to a system in the affected environment positioned to supply such data.

Notes

The Nashorn scripting engine that can be used to exploit this vulnerability was available by default in JDKs up to 14.0.2. As of JDK 15, this vulnerability can only be exploited if another scripting engine has been added, such as JEXL.

Vulnerable lookups:

1. script - executes expressions using the JVM script execution engine (javax.script)

2. dns - resolves dns records

3. url - loads values from urls, including from remote servers

PoC

final StringSubstitutor interpolator = StringSubstitutor.createInterpolator();
String out = interpolator.replace("${script:javascript:java.lang.Runtime.getRuntime().exec('touch /tmp/foo')}");
System.out.println(out);

Remediation

Upgrade org.apache.commons:commons-text to version 1.10.0 or higher.

References

• Apache Lists
• GitHub Commit
• GitHub PR
• GitHub Release
• Snyk Blog
• Nuclei Templates
• Exploit DB
• PoC in GitHub