SummaryAI-written · claude-haiku-5-5AI-written · claude-haiku-5-5Written by a language model from the source data on this page. Not reviewed by a person. Generated 29 Oct 2026.
The flaw is an incomplete fix in Apache Log4j2 (Apache Log4j 2.15.0) for untrusted-data handling, which lets Thread Context Map input be interpreted as a JNDI Lookup pattern. An attacker who controls Thread Context Map input can exploit it when the logging configuration uses a non-default Pattern Layout with a Context Lookup or a Thread Context Map pattern, causing an information leak and, in some environments, remote code execution, or local code execution in all environments.
Official description · NVDSource dataSource dataCopied from an authoritative feed: NVD, CVE.org, CISA KEV, FIRST EPSS or MITRE CTID mappings, or labelled by the annotators of a published dataset. Copied from NVD.
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.
Priority scorePatchfirst’s 0 to 100 ranking. It adds points for CISA KEV listing, ransomware use, EPSS, threat reports, public exploit code and CVSS. Every CVE page shows the breakdown.Breakdown
85.4 / 100
Exploited
Yes, in CISA KEV
Reports
2
Tactics
2/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 8 days before it was disclosed. Public exploit code (Metasploit) was available 5 days before disclosure.
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
Patch historyEarlier and later CVEs in the same code, in date order. It shows when a fix was bypassed or incomplete and which version finally fixed it.
A fix was bypassed or incomplete 2 times over 8 months. The latest fix listed for log4j-core is 2.25.3.
Same bug familyLinked by evidence that a fix failed or the same code was patched again. Oldest first.
CVE-2021-44228Log4j2 Remote Code Execution10 Dec 2021KEV
relatedHigh
Why these are linked: Link confidenceHow strong the evidence is that two CVEs are related. High: stated in the CVE text or linked in an advisory, or the same code was patched one release apart. Medium: the same code, or a version step plus a similar description. Low: similar description only.
CVE-2021-4104Deserialization of untrusted data in JMSAppender in Apache Log4j…14 Dec 2021
same family
This CVECVE-2021-45046Log4j2 Deserialization of Untrusted Data14 Dec 2021KEV
incomplete fixHigh
Why these are linked: Link confidenceHow strong the evidence is that two CVEs are related. High: stated in the CVE text or linked in an advisory, or the same code was patched one release apart. Medium: the same code, or a version step plus a similar description. Low: similar description only.
Stated in the CVE textIt was found that the original fix for log4j CVE-2021-44228 and CVE-2021-45046 in the OpenShift metering hive containers was incomplete, as not all JndiLookup.class files were removed.
CVE-2021-4125It was found that the original fix for log4j CVE-2021-44228 and…24 Aug 2022
Fixes in log4j-coreMaven package, by fixed version. Earlier and later fixes in the same package, not necessarily the same bug.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain orderSourceSource dataCopied from an authoritative feed: NVD, CVE.org, CISA KEV, FIRST EPSS or MITRE CTID mappings, or labelled by the annotators of a published dataset.2
Source dataSource dataCopied from an authoritative feed: NVD, CVE.org, CISA KEV, FIRST EPSS or MITRE CTID mappings, or labelled by the annotators of a published dataset. CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Deserialization of Untrusted Data.MITRE CTID mapping of the KEV entry · primary impact
CVE 2021-45046 is a Log4J-related vulnerability that could enable enables an attacker to cause Remote Code Execution or other effects in certain non-default configurations. This specific vulnerability has been reported to have been leveraged in cryptomining and ransomware operations.
Source dataSource dataCopied from an authoritative feed: NVD, CVE.org, CISA KEV, FIRST EPSS or MITRE CTID mappings, or labelled by the annotators of a published dataset. CTID Mappings Explorer KEV 07/28/2025 (ATT&CK 16.1); capability: Deserialization of Untrusted Data.MITRE CTID mapping of the KEV entry · follow-on activity
CVE 2021-45046 is a Log4J-related vulnerability that has been seen to be used in cryptomining and ransomware operations.
Detection
0 rules for this CVE · 112 general rules for its techniques
Rules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2021-45046 directly.
CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Command and Scripting InterpreterT105995general rules
From GitHub Security Advisories and OSVSourceSource dataCopied from an authoritative feed: NVD, CVE.org, CISA KEV, FIRST EPSS or MITRE CTID mappings, or labelled by the annotators of a published dataset. GitHub Security Advisories and OSV.
2 packages in 1 ecosystem. Main package: org.apache.logging.log4j:log4j-core.
Set the version to 2.17.1 or later in your pom.xml or build.gradle.
First fixed in 2.16.0 for CVE-2021-45046.
Affected versions, by release line
If you run
Upgrade to
2.13.0 up to 2.16.0
2.17.1first fix for this CVE: 2.16.0
2.4.0 up to 2.12.2
2.12.4first fix for this CVE: 2.12.2
All versions before 2.3.1
Still affected on this line by CVE-2017-5645 (fixed in 2.8.2, a newer line).
2.3.2first fix for this CVE: 2.3.1
“Up to” means the second version is the fix and is not affected.
Other packages that bundle this code (1)
Forks, repackagings and products that include the affected code. Each has its own fixed version.
Mavenorg.ops4j.pax.logging:pax-logging-log4j2
Affected: 2.0.0 up to 2.0.12; 1.11.0 up to 1.11.11; 1.10.0 up to 1.10.8; 1.8.0 up to 1.9.2Upgrade to 2.0.14 or later (older lines: 1.11.13, 1.10.9, 1.9.2)
Named in 2 threat reportsMachineMachine-matchedFound by keyword or pattern matching over threat-report text. Not reviewed by a person. Exact CVE id found in the report text.
2 reportsLinkedInMicrosoft
Reports are matched by finding the exact id CVE-2021-45046 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.
…above: vulnerabilities associated to Log4J were found on the VMWare Horizon Unified Access Gateways, UAG01 and UAG02, those were CVE-2021-44228 / CVE-2021-45046 / CVE-2021-45105 / CVE-2021-44832, which can potentially allow remote code execution on Unified Access Gateway by the low privilege non-root user named…
Apache Log4j2 (aka Log4Shell) (CVE-2021-44228 and CVE-2021-45046): Microsoft’s guidance for organizations using applications vulnerable to Log4Shell exploitation can be found here.