Apache Log4j vulnerabilities
3 known CVE vulnerabilities in Apache Log4j, translated and rated.
- CVE-2021-45046CriticalActively exploited
The fix for CVE-2021-44228 in Apache Log4j 2.15.0 was incomplete in certain non-default configurations. Attackers with control over Thread Context Map (MDC) input data when using a non-default Pattern Layout with Context Lookup (e.g., $${ctx:loginId}) or Thread Context Map pattern (%X, %mdc, %MDC) can craft malicious input using a JNDI Lookup pattern, leading to information leak and remote code execution in some environments and local code execution in all environments.
- CVE-2017-5645Critical
In Apache Log4j 2.x before version 2.8.2, when using the TCP socket server or UDP socket server to receive log events, a specially crafted binary payload can be sent that, when deserialized, can execute arbitrary code.
- CVE-2026-34481High
Apache Log4j JsonTemplateLayout up to version 2.25.3 produces invalid JSON output when log events contain non-finite floating-point values (NaN, Infinity, -Infinity), which violates RFC 8259. An attacker can exploit this if the application uses JsonTemplateLayout and logs a MapMessage or an object with a controlled floating-point value.