CVE-2021-45046
Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attack
- State
- Published
- Severity
- 9.0 Critical
- Published
- Dec 14, 2021
- Updated
- Oct 21, 2025
- Reserved
- Dec 14, 2021
Description
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) 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 an information leak and remote code execution in some environments and local code execution in all environments. Log4j 2.16.0 (Java 8) and 2.12.2 (Java 7) fix this issue by removing support for message lookup patterns and disabling JNDI functionality by default.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.0 Critical | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H | CISA-ADP |
Weaknesses
- CWE-917 Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
Affected Products
| Product | Versions |
|---|---|
Apache Log4jApache Software Foundation |
|
References
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032
- https://www.oracle.com/security-alerts/alert-cve-2021-44228.html
- https://www.cve.org/CVERecord?id=CVE-2021-44228
- [oss-security] 20211214 CVE-2021-45046: Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attackmailing-list
- https://logging.apache.org/log4j/2.x/security.html
- VU#930724third-party-advisory
- https://cert-portal.siemens.com/productcert/pdf/ssa-661247.pdf
- https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00646.html
- 20211210 Vulnerabilities in Apache Log4j Library Affecting Cisco Products: December 2021vendor-advisory
- [oss-security] 20211215 Re: CVE-2021-45046: Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attackmailing-list
- https://cert-portal.siemens.com/productcert/pdf/ssa-714170.pdf
- DSA-5022vendor-advisory
- [oss-security] 20211218 Re: CVE-2021-45046: Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attackmailing-list
- https://cert-portal.siemens.com/productcert/pdf/ssa-397453.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf
- FEDORA-2021-5c9d12a93evendor-advisory
- FEDORA-2021-abbe24e41cvendor-advisory
- https://www.oracle.com/security-alerts/cpujan2022.html
- https://www.oracle.com/security-alerts/cpuapr2022.html
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://security.gentoo.org/glsa/202310-16
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-45046government-resource
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