Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2021-45046

CVE-2021-45046CRITICAL

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

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS    %ile   KEV
   N   H   N   N  C  H  H  H    9.0   .9998   100.0   YES

AFFECTED
  Product       Versions         Fixed
  Apache Log4j  Apache Log4j2 –  —

TIMELINE
  Dec 14  Reserved by apache
  Dec 14  Published (CNA: apache)
  May 1   Added to CISA KEV, remediation due 2023-05-22

CWE-917 · CNA: apache · CVSS v3.1 · 22 references · KEV due May 22, 2023

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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
December 14, 2021	Reserved	Reserved by apache
December 14, 2021	Published	Published (CNA: apache)
May 1, 2023	KEV ADDED	Added to CISA KEV, remediation due 2023-05-22

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
Apache Software Foundation	Apache Log4j	—	Apache Log4j2	—

Weaknesses

CWE-917

References (22)

http://www.openwall.com/lists/oss-security/2021/12/14/4 [mailing-list, x_refsource_MLIST]
http://www.openwall.com/lists/oss-security/2021/12/15/3 [mailing-list, x_refsource_MLIST]
http://www.openwall.com/lists/oss-security/2021/12/18/1 [mailing-list, x_refsource_MLIST]
https://cert-portal.siemens.com/productcert/pdf/ssa-397453.pdf [x_refsource_CONFIRM]
https://cert-portal.siemens.com/productcert/pdf/ssa-479842.pdf [x_refsource_CONFIRM]
https://cert-portal.siemens.com/productcert/pdf/ssa-661247.pdf [x_refsource_CONFIRM]
https://cert-portal.siemens.com/productcert/pdf/ssa-714170.pdf [x_refsource_CONFIRM]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/EOKPQGV24RRBBI4TBZUDQMM4MEH7MXCY/ [vendor-advisory, x_refsource_FEDORA]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/SIG7FZULMNK2XF6FZRU4VWYDQXNMUGAJ/ [vendor-advisory, x_refsource_FEDORA]
https://logging.apache.org/log4j/2.x/security.html [x_refsource_CONFIRM]
https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0032 [x_refsource_CONFIRM]
https://security.gentoo.org/glsa/202310-16
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-apache-log4j-qRuKNEbd [vendor-advisory, x_refsource_CISCO]
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-45046 [government-resource]
https://www.cve.org/CVERecord?id=CVE-2021-44228 [x_refsource_MISC]
https://www.debian.org/security/2021/dsa-5022 [vendor-advisory, x_refsource_DEBIAN]
https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00646.html [x_refsource_CONFIRM]
https://www.kb.cert.org/vuls/id/930724 [third-party-advisory, x_refsource_CERT-VN]
https://www.oracle.com/security-alerts/alert-cve-2021-44228.html [x_refsource_CONFIRM]
https://www.oracle.com/security-alerts/cpuapr2022.html [x_refsource_MISC]
https://www.oracle.com/security-alerts/cpujan2022.html [x_refsource_MISC]
https://www.oracle.com/security-alerts/cpujul2022.html [x_refsource_MISC]

Authoritative record: CVE-2021-45046 at cve.org

Vendors: apache

Weaknesses: CWE-917

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-45046 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.