GHSA-6hg6-v5c8-fphq
Apache Log4j Core: `verifyHostName` attribute silently ignored in TLS configuration
At a glance
- Published
- Updated
- CVE
- CVE-2026-34477
- CVSS_V4
- 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
Description
The fix for CVE-2025-68161 was incomplete: it addressed hostname verification only when enabled via the [`log4j2.sslVerifyHostName`](https://logging.apache.org/log4j/2.x/manual/systemproperties.html#log4j2.sslVerifyHostName) system property, but not when configured through the [`verifyHostName`](https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName) attribute of the `<Ssl>` element. Although the `verifyHostName` configuration attribute was introduced in Log4j Core 2.12.0, it was silently ignored in all versions through 2.25.3, leaving TLS connections vulnerable to interception regardless of the configured value. A network-based attacker may be able to perform a man-in-the-middle attack when all of the following conditions are met: * An SMTP, Socket, or Syslog appender is in use. * TLS is configured via a nested <Ssl> element. * The attacker can present a certificate issued by a CA trusted by the appender's configured trust store, or by the default Java trust store if none is configured. This issue does not affect users of the HTTP appender, which uses a separate [`verifyHostname`](https://logging.apache.org/log4j/2.x/manual/appenders/network.html#HttpAppender-attr-verifyHostName) attribute that was not subject to this bug and verifies host names by default. Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue.
Affected packages
| Package | Versions |
|---|---|
| Maven · org.apache.logging.log4j:log4j-core | introduced 2.12.0, fixed 2.25.4 |
| Maven · org.apache.logging.log4j:log4j-core | introduced 3.0.0-alpha1, last affected 3.0.0-beta3 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2026-34477 ADVISORY
- https://github.com/apache/logging-log4j2/pull/4075 WEB
- https://github.com/apache/logging-log4j2 PACKAGE
- https://lists.apache.org/thread/lkx8cl46t2bvkcwfcb2pd43ygc097lq4 WEB
- https://logging.apache.org/cyclonedx/vdr.xml WEB
- https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName WEB
- https://logging.apache.org/security.html#CVE-2026-34477 WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |