Tracking Log4Shell (CVE-2021-44228): How Many Servers Are Still Vulnerable?

Background

In December 2021, the cybersecurity world was shaken by the disclosure of CVE-2021-44228, commonly known as Log4Shell. This critical vulnerability in Apache Log4j — a ubiquitous Java logging library — allowed remote code execution with a CVSS score of 10.0.

Current State

Using Zondex's vulnerability intelligence, we can track how many internet-facing servers still show signs of Log4Shell vulnerability.

Key Numbers

Our latest scan data reveals:

• Thousands of hosts still potentially affected
• Majority concentrated in a handful of countries
• Most common in Java-based web applications and middleware

Geographic Distribution

The countries with the highest concentration of potentially vulnerable hosts:

1. United States — largest absolute numbers due to hosting density
2. China — significant numbers in enterprise infrastructure
3. Germany — European hosting concentration
4. India — growing IT infrastructure with patching delays
5. Japan — enterprise Java deployments

Affected Services

Log4Shell primarily affects Java-based services. The most common affected services we observe:

• HTTP/HTTPS servers running Java application frameworks
• Elasticsearch instances
• Apache Solr deployments
• VMware products
• Apache Struts applications

Remediation Progress

While the initial patch rate was rapid, the long tail of remediation is concerning:

• Large enterprises largely patched within the first month
• Smaller organizations and embedded devices are slower to update
• Some systems remain unpatched due to end-of-life status

How to Check

Search for Log4Shell-affected hosts on Zondex:

• CVE-2021-44228 overview
• Search for affected hosts

Recommendations

1. Audit your Java applications for Log4j dependencies
2. Update to Log4j 2.17.1 or later
3. Monitor your attack surface using Zondex to verify patches are applied
4. Implement WAF rules to block known Log4Shell exploitation patterns

Conclusion

Log4Shell serves as a reminder that critical vulnerabilities can persist in internet-facing systems long after patches are available. Continuous monitoring and proactive vulnerability management are essential.