CVE Tools

CVE-2021-45046

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

Published: Dec 14, 2021Updated: Oct 27, 2025 Sources: CVE List NVD GHSA BDUCWE-917
9.0CVSSCRITICAL

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.

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:CC:HI:HA:H
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:HConfidentiality
High
I:HIntegrity
High
A:HAvailability
High

Weaknesses

Affected Products

сообщество свободного программного обеспеченияoss-projectOperating Systemsaka сообщество свободного программного обеспечения, fsf
red hat inc.commercialUSOperating Systemsaka red hat
and 70 more affected products View all →

Attack Graph

Products CVE Techniques Tactics

Click technique nodes to view MITRE ATT&CK details. Scroll to zoom, drag to pan.

Exploitability

CISA Known Exploited Vulnerability
Added to KEV:May 1, 2023
Remediation due:May 22, 2023
Ransomware:Known ransomware use

Required action: Apply updates per vendor instructions.

Official Patch Available
Workaround Available

MITRE ATT&CK

2 techniques
Execution
Initial Access
View detailed technique mapping

References

and 35 more references View all →

Timeline

Published
Dec 14, 2021
Added to CISA KEV
May 1, 2023
Last Updated
Oct 27, 2025

Unlock Complete Vulnerability Intelligence

Get the full picture for CVE-2021-45046 and every CVE in our database. Create a free account — no credit card required.

Create Free Account
Plain-language analysis
Impact assessment and exploitation scenario in plain English
Attack graph visualization
Interactive attack path and kill chain mapping
Exploit details & PoC links
ExploitDB, Metasploit, GitHub PoCs with direct links
Nuclei scanner templates
Ready-to-use vulnerability scanner templates
Full remediation guide
Patch instructions, workarounds, and compliance impact
Interactive AI chat
Ask questions about this vulnerability in natural language
Related vulnerabilities
Semantically similar CVEs and attack patterns
REST API & MCP access
Integrate vulnerability data into your workflows