CVE-2021-45046
Apache Log4j2 Deserialization of Untrusted Data Vulnerability
IN CISA KEV
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.
- Vendor
- Apache
- Product
- Log4j2
- CVSS 3.1
- 9 (critical), scored by NVD (primary)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- CVSS 3.1
- 9 (critical), scored by 134c704f-9b21-4f2e-91b3-4a467353bcc0CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
- CWE
- CWE-917
- Published
- 2021-12-14
- NVD modified
- 2026-06-17
- NVD status
- Analyzed
CISA KEV
- Date added
- 2023-05-01
- Due date
- 2023-05-22
- Ransomware use
- Known
- Required action
- Apply updates per vendor instructions.
EPSS
100% chance of exploitation in the next 30 days (percentile 99th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- www.openwall.com (Mailing List, Mitigation, Third Party Advisory)
- www.openwall.com (Mailing List, Third Party Advisory)
- www.openwall.com (Mailing List, Third Party Advisory)
- cert-portal.siemens.com (Third Party Advisory)
- cert-portal.siemens.com (Third Party Advisory)
- cert-portal.siemens.com (Third Party Advisory)
- cert-portal.siemens.com (Third Party Advisory)
- lists.fedoraproject.org (Mailing List, Release Notes)
- lists.fedoraproject.org (Mailing List, Release Notes)
- logging.apache.org (Mitigation, Release Notes, Vendor Advisory)
- psirt.global.sonicwall.com (Third Party Advisory)
- security.gentoo.org (Third Party Advisory)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.