CVE-2026-40023
5.3 · MEDIUMOverview
CVE-2026-40023 is a medium-severity vulnerability affecting apache log4cxx. It was published on April 10, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).
This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Apache Log4cxx's XMLLayout https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.html , in versions before 1.7.0, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets in log messages, NDC, and MDC property keys and values, producing invalid XML output. Conforming XML parsers must reject such documents with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records.
An attacker who can influence logged data can exploit this to suppress individual log records, impairing audit trails and detection of malicious activity.
Users are advised to upgrade to Apache Log4cxx 1.7.0, which fixes this issue.
Remediation
Check the references section for vendor advisories and patches from apache. Update log4cxx to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| apache | log4cxx | >= 0, < 1.7.0 | Affected |
References
Frequently Asked Questions
What is CVE-2026-40023?
CVE-2026-40023 is a medium-severity vulnerability affecting apache log4cxx. It was published on April 10, 2026 and has a CVSS 3.1 base score of 5.3 (MEDIUM).
How severe is CVE-2026-40023?
This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-40023?
Check the references section for vendor advisories and patches from apache. Update log4cxx to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-40023?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-40023 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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