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CVE-2021-45105

HIGH

Apache Log4j2 vulnerable to Improper Input Validation and Uncontrolled Recursion

Published December 18, 2021Updated June 9, 2026Source: osv

What Should I Do?

Fix in Your Next Sprint

This vulnerability has a 71.36% chance of being exploited within 30 days.

Summary

Apache Log4j2 versions 2.0-alpha1 through 2.16.0 (excluding 2.12.3) did not protect from uncontrolled recursion from self-referential lookups. This allows an attacker with control over Thread Context Map data to cause a denial of service when a crafted string is interpreted. This issue was fixed in Log4j 2.17.0 and 2.12.3. # Affected packages Only the `org.apache.logging.log4j:log4j-core` package is directly affected by this vulnerability. The `org.apache.logging.log4j:log4j-api` should be kept at the same version as the `org.apache.logging.log4j:log4j-core` package to ensure compatability if in use.

Remediation

Upgrade to the fixed version using your package manager.

Maven
Update org.apache.logging.log4j:log4j-core to 2.12.3 or later
<!-- Update pom.xml dependency version to 2.12.3 for org.apache.logging.log4j:log4j-core -->
Maven
Update org.apache.logging.log4j:log4j-core to 2.3.1 or later
<!-- Update pom.xml dependency version to 2.3.1 for org.apache.logging.log4j:log4j-core -->
Maven
Update org.ops4j.pax.logging:pax-logging-log4j2 to 1.11.12 or later
<!-- Update pom.xml dependency version to 1.11.12 for org.ops4j.pax.logging:pax-logging-log4j2 -->
Maven
Update org.ops4j.pax.logging:pax-logging-log4j2 to 1.10.9 or later
<!-- Update pom.xml dependency version to 1.10.9 for org.ops4j.pax.logging:pax-logging-log4j2 -->
Maven
Update org.ops4j.pax.logging:pax-logging-log4j2 to 1.9.2 or later
<!-- Update pom.xml dependency version to 1.9.2 for org.ops4j.pax.logging:pax-logging-log4j2 -->
Maven
Update org.ops4j.pax.logging:pax-logging-log4j2 to 2.0.13 or later
<!-- Update pom.xml dependency version to 2.0.13 for org.ops4j.pax.logging:pax-logging-log4j2 -->
Maven
Update org.apache.logging.log4j:log4j-core to 2.17.0 or later
<!-- Update pom.xml dependency version to 2.17.0 for org.apache.logging.log4j:log4j-core -->

After upgrading, run your dependency scanner again to confirm the vulnerability is resolved.

Affected Packages (7)

PackageEcosystemAffectedFixed In
org.apache.logging.log4j:log4j-core
Maven
2.10.0, 2.11.0, 2.11.1, 2.11.2 (+15 more)2.12.3
org.apache.logging.log4j:log4j-core
Maven
2.0, 2.0-alpha1, 2.0-alpha2, 2.0-beta1 (+15 more)2.3.1
org.ops4j.pax.logging:pax-logging-log4j2
Maven
1.11.0, 1.11.1, 1.11.10, 1.11.11 (+8 more)1.11.12
org.ops4j.pax.logging:pax-logging-log4j2
Maven
1.10.0, 1.10.1, 1.10.2, 1.10.3 (+5 more)1.10.9
org.ops4j.pax.logging:pax-logging-log4j2
Maven
1.8.0, 1.8.1, 1.8.2, 1.8.3 (+6 more)1.9.2
org.ops4j.pax.logging:pax-logging-log4j2
Maven
2.0.0, 2.0.1, 2.0.10, 2.0.11 (+9 more)2.0.13
org.apache.logging.log4j:log4j-core
Maven
2.13.0, 2.13.1, 2.13.2, 2.13.3 (+4 more)2.17.0

Vulnerability Classification

Common Weakness Enumeration (CWE) identifiers for this vulnerability type.

CVSS Score Breakdown

What the CVSS (Common Vulnerability Scoring System) 8.6 score means for each attack dimension.

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

References

Frequently Asked Questions

What is CVE-2021-45105?
Apache Log4j2 vulnerable to Improper Input Validation and Uncontrolled Recursion This vulnerability has been assigned a severity rating of HIGH (CVSS score: 8.6/10).
How do I check if my project is affected by CVE-2021-45105?
CVE-2021-45105 affects org.apache.logging.log4j:log4j-core and org.ops4j.pax.logging:pax-logging-log4j2. It has a 71.4% probability of exploitation within 30 days (EPSS score). Use GeekWala's free vulnerability scanner to check your dependencies against CVE-2021-45105 and 200,000+ other known vulnerabilities.

Severity & Exploitability

CVSS Score
8.6

High exploitability or significant impact. Prioritize remediation within days.

EPSS Score (30-day exploit probability)
71.36%
Higher than 99% of vulnerabilities

Also Known As

GHSA-p6xc-xr62-6r2g

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