VULNERABILITY INTELLIGENCE

CVE-2021-45046

CVSS score9 CRITICAL
EPSS probability99.98%
CISA KEVKnown exploited vulnerability
Published2021-12-14
Last modified2026-06-17
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Known Exploited Vulnerability

Apache Log4j2 Deserialization of Untrusted Data Vulnerability

Vendor / product: Apache / Log4j2

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.

Weakness classification

  • security@apache.org: CWE-917
  • nvd@nist.gov: CWE-917

Primary references