Apache Log4j attention 0day update immediately

A zero-day which affects the popular Apache Log4j (CVE-2021-44228) was released on December 9, 2021 and may allow Remote Code Execution (RCE).

This is already in use and anyone using Log4j should update to version 2.15.0 as soon as possible. The final version is already on download Apache.apache log4j

If the latest version is not available, Cloudflare has a WAF tweak that can also protect you. You must use a firewall and set the system property "log4j2.formatMsgNoLookups" to "true". or by removing the JndiLookup class from the class path.

Those who use Cloudflare WAF can also take advantage of three new rules that have been developed to mitigate any exploitation efforts:


RuleID Description Default Action
100514 (legacy WAF)
6b1cc72dff9746469d4695a474430f12 (new WAF)
Log4j Headers BLOCK
100515 (legacy WAF)
0c054d4e4dd5455c9ff8f01efe5abb10 (new WAF)
Log4j Body BLOCK
100516 (legacy WAF)
5f6744fa026a4638bda5b3d7d5e015dd (new WAF)


The firewall rules are three and they inspect HTTP headers, body and the URL respectively.

More details about the vulnerability can be found in the official Log4j security page.

Who is affected

Log4j is a powerful Java-based log library developed by the Apache Software Foundation.

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Written by giorgos

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