{"id":"CVE-2021-45046","aliases":["GHSA-7rjr-3q55-vv33"],"url":"https://o3.security/vulnerability/CVE-2021-45046","summary":"Incomplete fix for Apache Log4j vulnerability","details":"# Impact\n\nThe fix to address [CVE-2021-44228](https://nvd.nist.gov/vuln/detail/CVE-2021-44228) in Apache Log4j 2.15.0 was incomplete in certain non-default configurations. This could allow attackers with control over Thread Context Map (MDC) input data when the logging configuration uses a non-default Pattern Layout with either a Context Lookup (for example, $${ctx:loginId}) or a Thread Context Map pattern (%X, %mdc, or %MDC) to craft malicious input data using a JNDI Lookup pattern resulting in a remote code execution (RCE) attack. \n\n## Affected packages\nOnly 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.\n\n# Mitigation\n\nLog4j 2.16.0 fixes this issue by removing support for message lookup patterns and disabling JNDI functionality by default. This issue can be mitigated in prior releases (< 2.16.0) by removing the JndiLookup class from the classpath (example: zip -q -d log4j-core-*.jar org/apache/logging/log4j/core/lookup/JndiLookup.class).\n\nLog4j 2.15.0 restricts JNDI LDAP lookups to localhost by default. Note that previous mitigations involving configuration such as to set the system property `log4j2.formatMsgNoLookups` to `true` do NOT mitigate this specific vulnerability.","published":"2021-12-14T19:15:07.733Z","modified":"2026-10-20T10:55:43.793666086Z","cvss":{"score":9,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H"},"epss":{"score":0.99977,"percentile":0.99979,"asOf":"2026-09-17"},"cisaKev":{"dateAdded":"2023-05-01","dueDate":"2023-05-22","knownRansomwareCampaignUse":true},"exploitsKnown":13,"affectedPackages":[{"ecosystem":"Maven","name":"org.apache.logging.log4j:log4j-core","fixedVersion":"2.16.0"},{"ecosystem":"Maven","name":"org.apache.logging.log4j:log4j-core","fixedVersion":"2.12.2"},{"ecosystem":"Maven","name":"org.ops4j.pax.logging:pax-logging-log4j2","fixedVersion":"1.9.2"},{"ecosystem":"Maven","name":"org.ops4j.pax.logging:pax-logging-log4j2","fixedVersion":"1.10.8"},{"ecosystem":"Maven","name":"org.ops4j.pax.logging:pax-logging-log4j2","fixedVersion":"1.11.11"},{"ecosystem":"Maven","name":"org.ops4j.pax.logging:pax-logging-log4j2","fixedVersion":"2.0.12"},{"ecosystem":"Maven","name":"org.apache.logging.log4j:log4j-core","fixedVersion":"2.3.1"}],"fix":null,"references":[{"type":"WEB","url":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-45046"},{"type":"WEB","url":"https://www.cve.org/CVERecord?id=CVE-2021-44228"},{"type":"ADVISORY","url":"http://www.openwall.com/lists/oss-security/2021/12/14/4"},{"type":"ADVISORY","url":"http://www.openwall.com/lists/oss-security/2021/12/15/3"},{"type":"ADVISORY","url":"http://www.openwall.com/lists/oss-security/2021/12/18/1"},{"type":"ADVISORY","url":"https://cert-portal.siemens.com/productcert/pdf/ssa-397453.pdf"},{"type":"ADVISORY","url":"https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf"},{"type":"ADVISORY","url":"https://cert-portal.siemens.com/productcert/pdf/ssa-661247.pdf"},{"type":"ADVISORY","url":"https://cert-portal.siemens.com/productcert/pdf/ssa-714170.pdf"},{"type":"ADVISORY","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOKPQGV24RRBBI4TBZUDQMM4MEH7MXCY/"},{"type":"ADVISORY","url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SIG7FZULMNK2XF6FZRU4VWYDQXNMUGAJ/"},{"type":"ADVISORY","url":"https://logging.apache.org/log4j/2.x/security.html"},{"type":"ADVISORY","url":"https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032"},{"type":"ADVISORY","url":"https://security.gentoo.org/glsa/202310-16"},{"type":"ADVISORY","url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd"},{"type":"ADVISORY","url":"https://www.debian.org/security/2021/dsa-5022"},{"type":"ADVISORY","url":"https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00646.html"},{"type":"ADVISORY","url":"https://www.kb.cert.org/vuls/id/930724"},{"type":"ADVISORY","url":"https://www.oracle.com/security-alerts/alert-cve-2021-44228.html"},{"type":"ADVISORY","url":"https://www.oracle.com/security-alerts/cpuapr2022.html"},{"type":"ADVISORY","url":"https://www.oracle.com/security-alerts/cpujul2022.html"},{"type":"FIX","url":"https://www.oracle.com/security-alerts/cpujan2022.html"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-45046"},{"type":"WEB","url":"https://www.openwall.com/lists/oss-security/2021/12/18/1"},{"type":"WEB","url":"https://www.openwall.com/lists/oss-security/2021/12/15/3"},{"type":"WEB","url":"https://www.openwall.com/lists/oss-security/2021/12/14/4"},{"type":"WEB","url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd"},{"type":"WEB","url":"https://logging.apache.org/security.html#CVE-2021-45046"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SIG7FZULMNK2XF6FZRU4VWYDQXNMUGAJ"},{"type":"WEB","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/EOKPQGV24RRBBI4TBZUDQMM4MEH7MXCY"},{"type":"WEB","url":"https://github.com/apache/logging-log4j2/compare/rel/2.3...rel/2.3.1"}],"provenance":{"sources":["OSV.dev","CISA KEV","FIRST.org (EPSS)"],"lastVerified":"2026-10-20T10:55:43.793666086Z"}}