--- title: "CVE-2021-45046: Apache Log4j2 Thread Context Message… | CubePath" 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…" language: en source: https://cubepath.com/security/cve/CVE-2021-45046 --- # CVE-2021-45046: Apache Log4j2 Thread Context Message… | CubePath ## 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. Official description from the CVE record, published by apache. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2021-45046) ## Key data ### CVSS 3.1 Critical 9.0 Score published by CISA-ADP in the CVE record. CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H | Metric | Value | What it means | | ---------------------- | ------- | ----------------------------------------------------------------------------------------- | | Attack vector | Network | The vulnerable component can be reached over a network, possibly from the Internet. | | Attack complexity | High | The attack depends on conditions outside the attacker's control, so it takes preparation. | | Privileges required | None | No account or privileges are needed. | | User interaction | None | No action from any user is needed. | | Scope | Changed | The impact can reach other components beyond the vulnerable one. | | Confidentiality impact | High | Serious or total effect on the secrecy of data. | | Integrity impact | High | Serious or total effect on the trustworthiness of data. | | Availability impact | High | Serious or total effect on availability. | CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at [first.org/cvss](https://www.first.org/cvss/) . ### EPSS Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days. Score 0.99977 (99.97% probability) Percentile 99.97% Scores of Nov 10, 2026 Model v2026.06.15 ### CISA Known Exploited Vulnerabilities This CVE is listed in the CISA KEV catalog. Name in the catalog Apache Log4j2 Deserialization of Untrusted Data Vulnerability Added to the catalog May 1, 2023 Federal due date May 22, 2023 Ransomware campaigns Known use ### CISA assessment as of Feb 4, 2025 Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA. Exploitation Recorded by CISA as active Automatable no Technical impact total ### Weakness (CWE) CWE catalog version 5.0. CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license. - [CWE-917](https://cwe.mitre.org/data/definitions/917.html) Improper Neutralization of Special Elements used in an Expression Language Statement ## Affected products Products listed in the CVE record, as the CNA published them. - Apache Log4j - affected: Apache Log4j2 up to before 2.16.0 ## References Links listed in the CVE record. They lead to other sites, which CubePath does not control. - [psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032](https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032) - [oracle.com/security-alerts/alert-cve-2021-44228.html](https://www.oracle.com/security-alerts/alert-cve-2021-44228.html) - [cve.org/CVERecord?id=CVE-2021-44228](https://www.cve.org/CVERecord?id=CVE-2021-44228) - [\[oss-security\] 20211214 CVE-2021-45046: Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attack](http://www.openwall.com/lists/oss-security/2021/12/14/4) (openwall.com) mailing-list - [logging.apache.org/log4j/2.x/security.html](https://logging.apache.org/log4j/2.x/security.html) - [VU#930724](https://www.kb.cert.org/vuls/id/930724) (kb.cert.org) third-party-advisory - [cert-portal.siemens.com/productcert/pdf/ssa-661247.pdf](https://cert-portal.siemens.com/productcert/pdf/ssa-661247.pdf) - [intel.com/content/www/us/en/security-center/advisory/intel-…](https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00646.html) - [20211210 Vulnerabilities in Apache Log4j Library Affecting Cisco Products: December 2021](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd) (tools.cisco.com) vendor-advisory - [\[oss-security\] 20211215 Re: CVE-2021-45046: Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attack](http://www.openwall.com/lists/oss-security/2021/12/15/3) (openwall.com) mailing-list - [cert-portal.siemens.com/productcert/pdf/ssa-714170.pdf](https://cert-portal.siemens.com/productcert/pdf/ssa-714170.pdf) - [DSA-5022](https://www.debian.org/security/2021/dsa-5022) (debian.org) vendor-advisory - [\[oss-security\] 20211218 Re: CVE-2021-45046: Apache Log4j2 Thread Context Message Pattern and Context Lookup Pattern vulnerable to a denial of service attack](http://www.openwall.com/lists/oss-security/2021/12/18/1) (openwall.com) mailing-list - [cert-portal.siemens.com/productcert/pdf/ssa-397453.pdf](https://cert-portal.siemens.com/productcert/pdf/ssa-397453.pdf) - [cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf](https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf) - [FEDORA-2021-5c9d12a93e](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOKPQGV24RRBBI4TBZUDQMM4MEH7MXCY/) (lists.fedoraproject.org) vendor-advisory - [FEDORA-2021-abbe24e41c](https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SIG7FZULMNK2XF6FZRU4VWYDQXNMUGAJ/) (lists.fedoraproject.org) vendor-advisory - [oracle.com/security-alerts/cpujan2022.html](https://www.oracle.com/security-alerts/cpujan2022.html) - [oracle.com/security-alerts/cpuapr2022.html](https://www.oracle.com/security-alerts/cpuapr2022.html) - [oracle.com/security-alerts/cpujul2022.html](https://www.oracle.com/security-alerts/cpujul2022.html) - [security.gentoo.org/glsa/202310-16](https://security.gentoo.org/glsa/202310-16) ## Timeline 1. ID reserved Dec 14, 2021 2. Record published Dec 14, 2021 3. Added to CISA KEV May 1, 2023 4. Record last updated Oct 21, 2025 ## Look up another CVE ## About CubePath CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection. [Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection) Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:04 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)