Summary
Remote code injection in Log4j
Log4j versions prior to 2.16.0 are subject to a remote code execution vulnerability via the ldap JNDI parser.
As per Apache's Log4j security guide: Apache Log4j2 <=2.14.1 JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.16.0, this behavior has been disabled by default.
Log4j version 2.15.0 contained an earlier fix for the vulnerability, but that patch did not disable attacker-controlled JNDI lookups in all situations. For more information, see the Updated advice for version 2.16.0 section of this advisory.
Affected versions
Any Log4J version prior to v2.15.0 is affected to this specific issue.
The v1 branch of Log4J which is considered End Of Life (EOL) is vulnerable to other RCE vectors so the recommendation is to still update to 2.16.0 where possible.
Security releases
Additional backports of this fix have been made available in versions 2.3.1, 2.12.2, and 2.12.3
Affected packages
Only the org.apache.logging.log4j:log4j-core package is directly affected by this vulnerability. The org.apache.logging.log4j:log4j-api should be kept at the same version as the org.apache.logging.log4j:log4j-core package to ensure compatability if in use.
Remediation Advice
Updated advice for version 2.16.0
The Apache Logging Services team provided updated mitigation advice upon the release of version 2.16.0, which disables JNDI by default and completely removes support for message lookups.
Even in version 2.15.0, lookups used in layouts to provide specific pieces of context information will still recursively resolve, possibly triggering JNDI lookups. This problem is being tracked as CVE-2021-45046. More information is available on the GitHub Security Advisory for CVE-2021-45046.
Users who want to avoid attacker-controlled JNDI lookups but cannot upgrade to 2.16.0 must ensure that no such lookups resolve to attacker-provided data and ensure that the the JndiLookup class is not loaded.
Please note that Log4J v1 is End Of Life (EOL) and will not receive patches for this issue. Log4J v1 is also vulnerable to other RCE vectors and we recommend you migrate to Log4J 2.16.0 where possible.
Impact
Logging untrusted or user controlled data with a vulnerable version of Log4J may result in Remote Code Execution (RCE) against your application. This includes untrusted data included in logged errors such as exception traces, authentication failures, and other unexpected vectors of user controlled input.
The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.
CVE-2021-44228 has a CVSS score of 10.0 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (2.15.0, 2.12.2, 2.3.1, 1.9.2, 1.10.8, 1.11.10, 2.0.11); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
org.apache.logging.log4j:log4j-core to 2.15.0 or later; org.apache.logging.log4j:log4j-core to 2.12.2 or later; org.apache.logging.log4j:log4j-core to 2.3.1 or later; org.ops4j.pax.logging:pax-logging-log4j2 to 1.9.2 or later; org.ops4j.pax.logging:pax-logging-log4j2 to 1.10.8 or later; org.ops4j.pax.logging:pax-logging-log4j2 to 1.11.10 or later; org.ops4j.pax.logging:pax-logging-log4j2 to 2.0.11 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2021-44228? CVE-2021-44228 is a critical-severity improper input validation vulnerability in org.apache.logging.log4j:log4j-core (maven), affecting versions >= 2.13.0, < 2.15.0. It is fixed in 2.15.0, 2.12.2, 2.3.1, 1.9.2, 1.10.8, 1.11.10, 2.0.11. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
- How severe is CVE-2021-44228? CVE-2021-44228 has a CVSS score of 10.0 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2021-44228?
org.apache.logging.log4j:log4j-core(maven) (versions >= 2.13.0, < 2.15.0)com.guicedee.services:log4j-core(maven) (versions <= 1.2.1.2-jre17)org.xbib.elasticsearch:log4j(maven) (versions = 6.3.2.1)uk.co.nichesolutions.logging.log4j:log4j-core(maven) (versions = 2.6.3-CUSTOM)org.ops4j.pax.logging:pax-logging-log4j2(maven) (versions >= 1.8.0, < 1.9.2)
- Is there a fix for CVE-2021-44228? Yes. CVE-2021-44228 is fixed in 2.15.0, 2.12.2, 2.3.1, 1.9.2, 1.10.8, 1.11.10, 2.0.11. Upgrade to this version or later.
- Is CVE-2021-44228 exploitable, and should I be worried? Whether CVE-2021-44228 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2021-44228 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2021-44228?
- Upgrade
org.apache.logging.log4j:log4j-coreto 2.15.0 or later - Upgrade
org.apache.logging.log4j:log4j-coreto 2.12.2 or later - Upgrade
org.apache.logging.log4j:log4j-coreto 2.3.1 or later - Upgrade
org.ops4j.pax.logging:pax-logging-log4j2to 1.9.2 or later - Upgrade
org.ops4j.pax.logging:pax-logging-log4j2to 1.10.8 or later - Upgrade
org.ops4j.pax.logging:pax-logging-log4j2to 1.11.10 or later - Upgrade
org.ops4j.pax.logging:pax-logging-log4j2to 2.0.11 or later
- Upgrade