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CVE-2026-34477EXPLOITEDPATCHED
apache · log4j

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
apachelog4jmaven/org.apache.logging.log4j:log4j-core: >= 2.12.0, < 2.25.4, maven/org.apache.logging.log4j:log4j-core: >= 3.0.0-alpha1, <= 3.0.0-beta3

Also Affects

Downstream vendors/products affected by this vulnerability

VendorProductSourceConfidence
apachelog4jcert_advisory90%
mavenorg.apache.logging.log4j:log4j-coreGHSA85%

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 (6 articles)

Tier B
CERT-FR1d ago
Multiples vulnérabilités dans les produits IBM (05 juin 2026)
→ No new info (linked only)
Tier B
CERT-FR16d ago
Multiples vulnérabilités dans les produits Splunk (21 mai 2026)
→ No new info (linked only)
Tier A
Microsoft MSRC36d ago
CVE-2026-34477 Apache Log4j Core: verifyHostName attribute silently ignored in TLS configuration, allowing hostname verification bypass
→ No new info (linked only)
Tier B
BSI Advisories53d ago
[NEU] [mittel] Apache log4j: Mehrere Schwachstellen ermöglichen Manipulation von Dateien
→ No new info (linked only)
Tier C
VulDB56d 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-security56d 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
org.apache.logging.log4j:log4j-core@2.25.4
CWECWE-297
PublishedApr 10, 2026
Last enriched56d agov3
Trending Score57
Source articles6
Independent5
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 56d ago
v3Tier C56d ago

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

severityactivelyExploitedaffectedVersions
via VulDB
v2Tier C56d ago

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

affectedVersions
via oss-security
v156d ago

Initial creation