CVE-2021-45046: in the CISA KEV catalogue
Apache Log4j2 Deserialization of Untrusted Data Vulnerability. CISA added CVE-2021-45046 to the Known Exploited Vulnerabilities catalogue on 2023-05-01 with a default due date of 2023-05-22. Known ransomware campaign use: Known. Forensic triage flag: No.
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. (CISA description)
- Vendor / product
- Apache Log4j2
- CWE
- CWE-917
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 100%, percentile 99 (scored 2026-11-03)
EPSS puts nearly every time in 100 odds (100%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 99% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2021-45046 in the CISA KEV catalogue?
Yes. CISA added CVE-2021-45046 (Apache Log4j2 Deserialization of Untrusted Data Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-05-01. CISA's default due date for it is 2023-05-22.
Is CVE-2021-45046 used in ransomware attacks?
CISA marks known ransomware campaign use as Known for CVE-2021-45046.
What should I do about CVE-2021-45046?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2021-45046