CVE-2021-44228
Log4Shell: stopped at runtime
Waratek RASP already blocks this exploit at runtime, inside the JVM - with no application change, no vendor patch, and no downtime.
Published December 10, 2021 · Updated March 4, 2026
The vulnerability
Remote code execution via JNDI lookup
Apache Log4j 2 evaluates attacker-controlled ${jndi:...} lookups inside logged strings. Any input that reaches a log statement can force the JVM to fetch and execute code from a remote LDAP or RMI server, giving an unauthenticated attacker full remote code execution.
Running an affected version? We can help.
Waratek RASP shields the vulnerable code in production - the exploit is blocked at runtime with no library upgrade, no redeploy, and no downtime. We can have you covered fast.
How Waratek RASP stops it
Blocked at runtime by Waratek RASP
Waratek RASP ships a patch rule that blocks exploitation at the exact point the dangerous operation is attempted, inside the JVM.
Runtime, not perimeter
Waratek RASP acts inside the JVM at the exact call that turns input into code, so obfuscated and encoded payloads are caught where a WAF misses them.
No code changes
Protection is applied as a rule at runtime. No source edits, no recompilation, no library upgrade, and no application restart required.
Zero false positives
Rules target the specific unsafe behaviour of the exploit, so legitimate traffic keeps flowing while the attack is blocked and logged.
| Mod | Rules | Enable |
|---|---|---|
| Log4Shell protectionCVE-2021-44228 · JNDI injection / unsafe deserialization | 1 | |
| SQL Injection protectionQuery manipulation | 4 | |
| Path Traversal protectionUnsafe file access | 3 |
Flip one toggle in the Waratek Portal. The protection deploys to every attached application, with no restart.
Common questions
Log4Shell FAQ
Is Log4Shell (CVE-2021-44228) exploitable?
CVE-2021-44228 carries a CVSS 10/10 (CRITICAL) rating and affects Apache Log4j 2 (log4j-core) 2.0-beta9 through 2.14.1. Apache Log4j 2 evaluates attacker-controlled ${jndi:...} lookups inside logged strings. Any input that reaches a log statement can force the JVM to fetch and execute code from a remote LDAP or RMI server, giving an unauthenticated attacker full remote code execution. It is listed in CISA's Known Exploited Vulnerabilities catalog, with known ransomware campaign use.
How does Waratek mitigate Log4Shell (CVE-2021-44228)?
Waratek RASP blocks exploitation of Log4Shell (CVE-2021-44228) inside the JVM at runtime, with no application code changes, no vendor patch and no restart.
How quickly was Log4Shell (CVE-2021-44228) exploited after disclosure?
A working exploit for CVE-2021-44228 was published within hours of its NVD disclosure, on December 10, 2021.
Protect your apps in production
Get protected against Log4Shell - without code changes or redeploying
Book a call and we’ll show you how Waratek RASP shields your running applications against CVE-2021-44228 and attacks like it, and get you covered in production.