Threat Intelligence / CVE / CVE-2021-44228

CVE-2021-44228 — Apache Log4j

CISA KEVRansomware
CVSS v3.1 10 (CRITICAL) · EPSS 94.3% (higher than 99.9% of all scored CVEs) · Priority 10/10 · Published 2021-12-10

As of 2026-02-20, CVE-2021-44228 is a CRITICAL-severity vulnerability in Apache Log4j, CVSS v3.1 10, EPSS 94.3% (99.9th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-12-10), with a US federal remediation deadline of 2021-12-24, and CISA links it to known ransomware campaigns. Threadlinqs Intelligence links 5 tracked threat campaigns to CVE-2021-44228, most recently “DragonForce Ransomware Attack on RubberMill, Inc. — ~340GB Data Exfiltration Including PII, Credentials, CAD Files with Defense Mil-Spec References”.

Last updated: 2026-02-20

What is CVE-2021-44228?

Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.

The record classifies CVE-2021-44228 under weakness classes CWE-20, CWE-400, CWE-502, CWE-917. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 381 affected-product entries are recorded, across 2 vendors, listed below. The identifier was first published 1738 days ago.

Severity and exploitation probability

CVSS v3.1 base score
10 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS (FIRST)
94.3% probability of exploitation in the next 30 days, higher than 99.9% of all scored CVEs
CISA KEV
Listed since 2021-12-10, federal remediation deadline 2021-12-24 — used in known ransomware campaigns
Threadlinqs priority
10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
Published
2021-12-10, last modified 2026-02-20

Is CVE-2021-44228 being exploited?

CISA added CVE-2021-44228 to the Known Exploited Vulnerabilities catalog on 2021-12-10, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2021-12-24 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

Showing 25 of 381 recorded product entries.

How to fix CVE-2021-44228

Vendor advisory: https://logging.apache.org/log4j/2.x/security.html. Because CVE-2021-44228 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2021-12-24. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2021-44228

5 tracked threats in the Threadlinqs corpus reference CVE-2021-44228, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2021-44228 are available via the Threadlinqs MCP server (Purple tier). View plans →

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