CVE-2021-45046
CRITICALCISA KEVEPSS 100th pctlDescription
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.
How to fix
This vulnerability affects an unusually large number of packages. The highest-confidence fixes are shown above; the full list is longer. Check the referenced advisories for complete coverage.
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
Apache Log4j2 Deserialization of Untrusted Data Vulnerability
Apache Log4j2 contains a deserialization of untrusted data vulnerability due to the incomplete fix of CVE-2021-44228, where the Thread Context Lookup Pattern is vulnerable to remote code execution in certain non-default configurations.
Apply updates per vendor instructions.
Remediation due: 2023-05-22
Associated with ransomware campaigns
References
Related Vulnerabilities
Other CWE-917 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-26134 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2021-44228 | Critical | 10.0 | 100% | KEV + Ransom | Fix |
| CVE-2021-26084 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
| CVE-2022-22963 | Critical | 9.8 | 100% | KEV | - |
| CVE-2020-10199 | High | 8.8 | 99% | KEV | Fix |
| CVE-2022-22947 | Critical | 10.0 | 98% | KEV | Fix |
Common questions
How do I fix CVE-2021-45046?
Published advisories record a fix for 129 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-45046 being actively exploited?
Yes. CVE-2021-45046 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. CISA has also linked it to known ransomware campaigns. US federal agencies were required to remediate it by 2023-05-22. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2021-45046?
CVE-2021-45046 has a CVSS v3 base score of 9.0, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-45046 affect?
Published advisories record a fix for aws-kinesis-agent (Amazon), java-1.7.0-openjdk (Amazon), java-1.7.0-openjdk-accessibility (Amazon), java-1.7.0-openjdk-debuginfo (Amazon), and 125 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2021-45046
Markdown
[](https://tridentstack.com/cve/CVE-2021-45046)HTML
<a href="https://tridentstack.com/cve/CVE-2021-45046"><img src="https://tridentstack.com/cve/badge/CVE-2021-45046.svg" alt="CVE-2021-45046"></a>This vulnerability is actively exploited in the wild
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.