CVE DATABASE / CVE-2021-45046
CVE-2021-45046
Apache Log4j2 Deserialization of Untrusted Data Vulnerability
Confirmed exploited in the wild. Added 2023-05-01.
Federal remediation due 2023-05-22.
Required action: Apply updates per vendor instructions.
Summary
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.
CVSS 3.1 breakdown
| Base score | 9 (CRITICAL) |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| Attack vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | CHANGED |
| Confidentiality | HIGH |
| Integrity | HIGH |
| Availability | HIGH |
Weakness type (CWE)
Affected products
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References
- http://www.openwall.com/lists/oss-security/2021/12/14/4
- http://www.openwall.com/lists/oss-security/2021/12/15/3
- http://www.openwall.com/lists/oss-security/2021/12/18/1
- https://cert-portal.siemens.com/productcert/pdf/ssa-397453.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-661247.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-714170.pdf
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOKPQGV24RRBBI4TBZUDQMM4MEH7MXCY/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SIG7FZULMNK2XF6FZRU4VWYDQXNMUGAJ/
- https://logging.apache.org/log4j/2.x/security.html
- https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032
- https://security.gentoo.org/glsa/202310-16
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd
- https://www.cve.org/CVERecord?id=CVE-2021-44228
- https://www.debian.org/security/2021/dsa-5022
Data: NIST NVD + CISA KEV. NVD last modified 2025-10-27. Always verify against the vendor advisory before acting.