CVE-2026-34480 (Medium) detected in log4j-core-2.11.2.jar

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CVE-2026-34480 - Medium Severity Vulnerability

Vulnerable Library - log4j-core-2.11.2.jar

The Apache Log4j Implementation

Library home page: https://www.apache.org/

Path to dependency file: /pom.xml

Path to vulnerable library: /home/wss-scanner/.m2/repository/org/apache/logging/log4j/log4j-core/2.11.2/log4j-core-2.11.2.jar

Dependency Hierarchy:

• solr-velocity-8.3.1.jar (Root Library)
  • ❌ log4j-core-2.11.2.jar (Vulnerable Library)

Found in HEAD commit: bada63441522c15b923cde8a080ad10d787106e1

Found in base branch: master

Vulnerability Details

Apache Log4j Core's XmlLayout https://logging.apache.org/log4j/2.x/manual/layouts.html#XmlLayout , in versions up to and including 2.25.3, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets producing invalid XML output whenever a log message or MDC value contains such characters.
The impact depends on the StAX implementation in use:

• JRE built-in StAX: Forbidden characters are silently written to the output, producing malformed XML. Conforming parsers must reject such documents with a fatal error, which may cause downstream log-processing systems to drop the affected records.
• Alternative StAX implementations (e.g., Woodstox https://github.com/FasterXML/woodstox , a transitive dependency of the Jackson XML Dataformat module): An exception is thrown during the logging call, and the log event is never delivered to its intended appender, only to Log4j's internal status logger.
  Users are advised to upgrade to Apache Log4j Core 2.25.4, which corrects this issue by sanitizing forbidden characters before XML output.

Publish Date: 2026-04-10

URL: CVE-2026-34480

CVSS 3 Score Details (5.8)

Base Score Metrics:

• Exploitability Metrics:
  • Attack Vector: Network
  • Attack Complexity: Low
  • Privileges Required: None
  • User Interaction: None
  • Scope: Changed
• Impact Metrics:
  • Confidentiality Impact: None
  • Integrity Impact: Low
  • Availability Impact: None

For more information on CVSS3 Scores, click here.

Suggested Fix

Type: Upgrade version

Release Date: 2026-04-10

Fix Resolution (org.apache.logging.log4j:log4j-core): 2.25.4

Direct dependency fix Resolution (org.apache.solr:solr-velocity): 8.5.0

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⛑️ Automatic Remediation will be attempted for this issue.