Apache Log4j does not verify the TLS hostname in its Socket Appender
The Socket Appender in Apache Log4j Core versions 2.0-beta9 through 2.25.2 does not perform TLS hostname verification of the peer certificate, even when the verifyHostName configuration attribute or the log4j2.sslVerifyHostName system property is set to true.
This issue may allow a man-in-the-middle attacker to intercept or redirect log traffic under the following conditions:
- The attacker is able to intercept or redirect network traffic between the client and the log receiver.
- The attacker can present a server certificate issued by a certification authority trusted by the Socket Appender’s configured trust store (or by the default Java trust store if no custom trust store is configured).
Users are advised to upgrade to Apache Log4j Core version 2.25.3, which addresses this issue.
As an alternative mitigation, the Socket Appender may be configured to use a private or restricted trust root to limit the set of trusted certificates.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.apache.logging.log4j:log4j-core | >= 2.0-beta9, < 2.25.3 | 2.25.3 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-68161
- https://github.com/apache/logging-log4j2/pull/4002
- https://github.com/apache/logging-log4j2/commit/3b93748497e1adbbd027fda8a5e7268ec5d0d578
- https://github.com/apache/logging-log4j2
- https://lists.apache.org/thread/xr33kyxq3sl67lwb61ggvm1fzc8k7dvx
- https://logging.apache.org/cyclonedx/vdr.xml
- https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName
- https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName
- https://logging.apache.org/security.html#CVE-2025-68161
- http://www.openwall.com/lists/oss-security/2025/12/18/1
- CVSS vector
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:L/SA:N- Weakness (CWE)
CWE-297- Platform
- Java / Kotlin (Maven)
- Package
org.apache.logging.log4j:log4j-core- Disclosed
- 18.12.2025
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-vc5p-v9hr-52mj - CC BY 4.0
Vulnerability history: org.apache.logging.log4j:log4j-core
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 11
- First → latest
- 01.2020 04.2026
- Without a fix
- 0
- Exploited in attacks
- 2
Severity breakdown
- Critical 3
- High 2
- Medium 5
- Low 1
Disclosures per year
- 2020: 2
- 2021: 3
- 2022: 1
- 2023: 1
- 2024: 0
- 2025: 1
- 2026: 3
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Apache Log4j does not verify the TLS hostname in its Socket Appender this entry
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