CVE-2021-44228Known exploitationPublic exploitNetwork attack vector

Remote code execution via attacker-controlled JNDI lookups

Published Dec 10, 2021 · Updated Oct 21, 2025

Remote code execution in Apache Log4j 2's log4j-core allows remote attackers to run arbitrary code through crafted log data. The message-lookup path resolves attacker-controlled JNDI references through LDAP and loads code returned by the attacker's endpoint. Exploitation requires an application using an affected log4j-core release to log attacker-controlled text while message lookup substitution is enabled.

CVSS severity10.0
Critical
EPSS probability100.00%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Remote code execution in Apache Log4j 2's log4j-core allows remote attackers to run arbitrary code through crafted log data. The message-lookup path resolves attacker-controlled JNDI references through LDAP and loads code returned by the attacker's endpoint. Exploitation requires an application using an affected log4j-core release to log attacker-controlled text while message lookup substitution is enabled.

The record

CVE
CVE-2021-44228
Published
Dec 10, 2021
Updated
Oct 21, 2025
Vendor
Apache Software Foundation
Product
Apache Log4j 2
Classifications
CWE-502, CWE-917, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 1, 2021Exploitation reportedActive Log4Shell exploitation and widespread scanning
  2. Dec 10, 2021CVE publishedPublication date reported by the CVE source.
  3. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.0-beta9 <log4j-core* changes=[{"at":"2.3.1","status":"unaffected"},{"at":"2.4","status":"affected"},{"at":"2.12.2","status":"unaffected"},{"at":"2.13.0","status":"affected"},{"at":"2.15.0","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apache Software Foundation · Apache Log4j 2version=2.0-beta9 <log4j-core* changes=[{"at":"2.3.1","status":"unaffected"},{"at":"2.4","status":"affected"},{"at":"2.12.2","status":"unaffected"},{"at":"2.13.0","status":"affected"},{"at":"2.15.0","status":"unaffected"}]

Published CVSS scores

10.0NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
10.0Apache Software FoundationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
9.3NIST National Vulnerability DatabaseAV:N/AC:M/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsShadowserver observations through Sep 16, 2026. Gaps indicate unavailable data.
Sep 10, 2026Sep 16, 2026
View daily counts
Reporting dayUnique IPs
Sep 10, 202645
Sep 11, 202641
Sep 12, 202635
Sep 13, 202636
Sep 14, 202632
Sep 15, 202627
Sep 16, 202668
Latest reporting daySep 16, 2026
Latest daily unique IPs68
Prior 30-day average41.3
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
CWE-917Improper Neutralization of Special Elements used in an Expression Language Statement ('Expression Language Injection')
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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