Incomplete fix for Apache Log4j vulnerability
CISA confirms exploitation of this vulnerability in real attacks. Prioritise checking whether your application is affected. CISA KEV · CC0 1.0
Impact
The fix to address 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.
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.
Mitigation
Log4j 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).
Log4j 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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.apache.logging.log4j:log4j-core | >= 2.13.0, < 2.16.0, >= 2.4.0, < 2.12.2, < 2.3.1 | 2.16.0, 2.12.2, 2.3.1 |
| Java / Kotlin (Maven) | org.ops4j.pax.logging:pax-logging-log4j2 | >= 1.8.0, < 1.9.2, >= 1.10.0, < 1.10.8, >= 1.11.0, < 1.11.11, >= 2.0.0, < 2.0.12 | 1.9.2, 1.10.8, 1.11.11, 2.0.12 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2021-45046
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/alert-cve-2021-44228.html
- https://www.openwall.com/lists/oss-security/2021/12/18/1
- https://www.openwall.com/lists/oss-security/2021/12/15/3
- https://www.openwall.com/lists/oss-security/2021/12/14/4
- https://www.kb.cert.org/vuls/id/930724
- https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00646.html
- https://www.debian.org/security/2021/dsa-5022
- https://www.cve.org/CVERecord?id=CVE-2021-44228
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-45046
- https://security.gentoo.org/glsa/202310-16
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032
- https://logging.apache.org/security.html#CVE-2021-45046
- https://logging.apache.org/log4j/2.x/security.html
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/SIG7FZULMNK2XF6FZRU4VWYDQXNMUGAJ
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/EOKPQGV24RRBBI4TBZUDQMM4MEH7MXCY
- https://github.com/apache/logging-log4j2/compare/rel/2.3...rel/2.3.1
- https://cert-portal.siemens.com/productcert/pdf/ssa-714170.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-661247.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-397453.pdf
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H- Weakness (CWE)
CWE-502, CWE-917- Platform
- Java / Kotlin (Maven)
- Package
org.apache.logging.log4j:log4j-core, org.ops4j.pax.logging:pax-logging-log4j2- Disclosed
- 14.12.2021
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-7rjr-3q55-vv33 - CC BY 4.0
Vulnerability history: org.apache.logging.log4j:log4j-core
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 11
- First → latest
- 01.2020 04.2026
- Without a fix
- 0
- Exploited in attacks
- 2
Severity breakdown
- Critical 3
- High 2
- Medium 5
- Low 1
Disclosures per year
- 2020: 2
- 2021: 3
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 1
- 2026: 3
-
Incomplete fix for Apache Log4j vulnerability this entry
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