CVE-2021-45046 - CVE House
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Status published Unknown CVE-2021-45046

Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attack

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

Affected Vendor

Apache Software Foundation

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Affected Software

Apache Log4j
Vulnerable Versions:
Apache Log4j2

Timeline

Official Publish: December 14th, 2021
Last Modified: October 21st, 2025
Added to House: July 21st, 2026

CVSS Vectors

No vector data available

Weaknesses (CWE)

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.