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Improper validation of certificate with host mismatch in Apache Log4j SMTP appender

Low severity GitHub Reviewed Published Jun 5, 2020 to the GitHub Advisory Database • Updated Jun 9, 2026

Package

maven org.apache.logging.log4j:log4j (Maven)

Affected versions

>= 2.13.0, < 2.13.2
>= 2.4.0, < 2.12.3
< 2.3.2

Patched versions

2.13.2
2.12.3
2.3.2
maven org.apache.logging.log4j:log4j-core (Maven)
>= 2.13.0, < 2.13.2
>= 2.4.0, < 2.12.3
< 2.3.2
2.13.2
2.12.3
2.3.2

Description

Improper validation of certificate with host mismatch in Apache Log4j SMTP appender prior to version 2.13.2. This could allow an SMTPS connection to be intercepted by a man-in-the-middle attack which could leak any log messages sent through that appender.

References

Published by the National Vulnerability Database Apr 27, 2020
Reviewed Jun 4, 2020
Published to the GitHub Advisory Database Jun 5, 2020
Last updated Jun 9, 2026

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(94th percentile)

Weaknesses

Improper Certificate Validation

The product does not validate, or incorrectly validates, a certificate. Learn more on MITRE.

CVE ID

CVE-2020-9488

GHSA ID

GHSA-vwqq-5vrc-xw9h

Source code

No known source code

Credits

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