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CVE-2026-34477EXPLOITEDPATCHED
Apache Software Foundation · Apache Log4j Core

Apache Log4j Core: verifyHostName attribute silently ignored in TLS configuration, allowing hostname verification bypass

Description

The fix for CVE-2025-68161 https://logging.apache.org/security.html#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 Products

VendorProductVersions
Apache Software FoundationApache Log4j Core2.12.0, 3.0.0-alpha1, 3.0.0-beta3

References

  • https://github.com/apache/logging-log4j2/pull/4075(patch)
  • https://logging.apache.org/security.html#CVE-2026-34477(vendor-advisory)
  • https://logging.apache.org/cyclonedx/vdr.xml(vendor-advisory)
  • https://logging.apache.org/log4j/2.x/manual/appenders/network.html#SslConfiguration-attr-verifyHostName(related)
  • https://lists.apache.org/thread/lkx8cl46t2bvkcwfcb2pd43ygc097lq4(vendor-advisory)

Related News (2 articles)

Tier C
VulDB3h ago
CVE-2026-34477 | Apache Log4j Core up to 2.25.3/3.0.0-beta3 log4j2.sslVerifyHostName certificate host validation
→ No new info (linked only)
Tier C
oss-security5h ago
CVE-2026-34477: Apache Log4j Core: verifyHostName attribute silently ignored in TLS configuration, allowing hostname verification bypass
→ No new info (linked only)
CISA KEV❌ No
Actively exploited✅ Yes
Patch available
2.25.4
CWECWE-297
PublishedApr 10, 2026
Last enriched2h agov3
Trending Score61
Source articles2
Independent2
Info Completeness8/14
Missing: cvss, epss, kev, exploit, iocs, mitre_attack

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Verification

State: verified
Confidence: 0%

Vulnerability Timeline

CVE Published
Apr 10, 2026
Discovered by ZDM
Apr 10, 2026
Updated: affectedVersions
Apr 10, 2026
Actively Exploited
Apr 10, 2026
Patch Available
Apr 10, 2026
Updated: severity, activelyExploited, affectedVersions
Apr 10, 2026

Version History

v3
Last enriched 2h ago
v3Tier C2h ago

Updated severity to CRITICAL, marked as actively exploited, and added new affected version 3.0.0-beta3.

severityactivelyExploitedaffectedVersions
via VulDB
v2Tier C5h ago

Updated severity from NONE to MODERATE and added new affected version 3.0.0-beta3.

affectedVersions
via oss-security
v15h ago

Initial creation