Apache LOG4J vulnerabilities

20 CVEs affecting Apache LOG4J, 2 known to be exploited (CISA KEV), with EPSS scores. Latest: CVE-2026-49844, published 2026-07-10.

Highest priority

Known exploited (CISA KEV) first, then by EPSS exploit probability.

CVE-2021-44228: Apache Log4j2 Remote Code Execution Vulnerability, published 2021-12-10. Critical severity, CVSS 10.0. Actively exploited: in CISA KEV since 2021-12-10. EPSS: 100% chance of exploitation in the next 30 days. Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker…
CVE-2021-45046: Apache Log4j2 Deserialization of Untrusted Data Vulnerability, published 2021-12-14. Critical severity, CVSS 9.0. Actively exploited: in CISA KEV since 2023-05-01. EPSS: 100% chance of exploitation in the next 30 days. It was found that the fix to address CVE-2021-44228 in Apache Log4j 2.15.0 was incomplete in certain non-default configurations. This could allows attackers with control over Thread Context Map (MDC)…
CVE-2021-45105, published 2021-12-18. Medium severity, CVSS 5.9. EPSS: 100% chance of exploitation in the next 30 days. Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3 and 2.3.1) did not protect from uncontrolled recursion from self-referential lookups. This allows an attacker with control over…
CVE-2021-44832, published 2021-12-28. Medium severity, CVSS 6.6. EPSS: 97.9% chance of exploitation in the next 30 days. Apache Log4j2 versions 2.0-beta7 through 2.17.0 (excluding security fix releases 2.3.2 and 2.12.4) are vulnerable to a remote code execution (RCE) attack when a configuration uses a JDBC Appender…
CVE-2017-5645, published 2017-04-17. Critical severity, CVSS 9.8. EPSS: 89.8% chance of exploitation in the next 30 days. In Apache Log4j 2.x before 2.8.2, when using the TCP socket server or UDP socket server to receive serialized log events from another application, a specially crafted binary payload can be sent that,…
CVE-2021-4104, published 2021-12-14. High severity, CVSS 7.5. EPSS: 80.6% chance of exploitation in the next 30 days. JMSAppender in Log4j 1.2 is vulnerable to deserialization of untrusted data when the attacker has write access to the Log4j configuration. The attacker can provide TopicBindingName and…
CVE-2019-17571, published 2019-12-20. Critical severity, CVSS 9.8. EPSS: 70% chance of exploitation in the next 30 days. Included in Log4j 1.2 is a SocketServer class that is vulnerable to deserialization of untrusted data which can be exploited to remotely execute arbitrary code when combined with a deserialization…
CVE-2022-23305, published 2022-01-18. Critical severity, CVSS 9.8. EPSS: 66.5% chance of exploitation in the next 30 days. By design, the JDBCAppender in Log4j 1.2.x accepts an SQL statement as a configuration parameter where the values to be inserted are converters from PatternLayout. The message converter, %m, is…
CVE-2022-23302, published 2022-01-18. High severity, CVSS 8.8. EPSS: 63.6% chance of exploitation in the next 30 days. JMSSink in all versions of Log4j 1.x is vulnerable to deserialization of untrusted data when the attacker has write access to the Log4j configuration or if the configuration references an LDAP…
CVE-2022-23307, published 2022-01-18. High severity, CVSS 8.8. EPSS: 54.4% chance of exploitation in the next 30 days. CVE-2020-9493 identified a deserialization issue that was present in Apache Chainsaw. Prior to Chainsaw V2.0 Chainsaw was a component of Apache Log4j 1.2.x where the same issue exists.

Latest

CVE-2026-49844, published 2026-07-10. Medium severity, CVSS 5.9. EPSS: 0.8% chance of exploitation in the next 30 days. Improper encoding of non-finite floating-point values during MapMessage JSON serialization in Apache Log4j API produces output that is not valid JSON. This issue affects Apache Log4j API versions…
CVE-2026-34481, published 2026-04-10. High severity, CVSS 7.5. EPSS: 0.9% chance of exploitation in the next 30 days. Apache Log4j's JsonTemplateLayout https://logging.apache.org/log4j/2.x/manual/json-template-layout.html , in versions up to and including 2.25.3, produces invalid JSON output when log events contain…
CVE-2026-34480, published 2026-04-10. High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days. Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0…
CVE-2026-34479, published 2026-04-10. High severity, CVSS 7.5. EPSS: 0.9% chance of exploitation in the next 30 days. The Log4j1XmlLayout from the Apache Log4j 1-to-Log4j 2 bridge fails to escape characters forbidden by the XML 1.0 standard, producing malformed XML output. Conforming XML parsers are required to…
CVE-2026-34478, published 2026-04-10. High severity, CVSS 7.5. EPSS: 1.2% chance of exploitation in the next 30 days. Apache Log4j Core's Rfc5424Layout https://logging.apache.org/log4j/2.x/manual/layouts.html#RFC5424Layout , in versions 2.21.0 through 2.25.3, is vulnerable to log injection via CRLF sequences due to…
CVE-2026-34477, published 2026-04-10. Medium severity, CVSS 5.9. EPSS: 0.5% chance of exploitation in the next 30 days. The fix for CVE-2025-68161 https://logging.apache.org/security.html#CVE-2025-68161 was incomplete: it addressed hostname verification only when enabled via the log4j2.sslVerifyHostName…
CVE-2025-68161, published 2025-12-18. Medium severity, CVSS 4.8. EPSS: 0.8% chance of exploitation in the next 30 days. The Socket Appender in Apache Log4j Core versions 2.0-beta9 through 2.25.2 does not perform TLS hostname verification of the peer certificate, even when the verifyHostName…
CVE-2023-26464, published 2023-03-10. High severity, CVSS 7.5. EPSS: 1.9% chance of exploitation in the next 30 days. ** UNSUPPORTED WHEN ASSIGNED ** When using the Chainsaw or SocketAppender components with Log4j 1.x on JRE less than 1.7, an attacker that manages to cause a logging entry involving a…