known ransomware use

Apache Log4j2 Deserialization of Untrusted Data Vulnerability

Added to KEV
2023-05-01
Federal due date
2023-05-22
Vendor
Apache
Product
Log4j2
EPSS
100.0th percentile (score 0.943, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Known
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2021-45046

CISA short description

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.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.