Apache: >> Log4cxx >> 1.2.0 Security Vulnerabilities
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.
CVSS Score
6.3
EPSS Score
0.003
Published
2026-04-10
Improper Output Neutralization for Logs vulnerability in Apache Log4cxx.
When using JSONLayout, not all payload bytes are properly escaped. If an attacker-supplied message contains certain non-printable characters, these will be passed along in the message and written out as part of the JSON message. This may prevent applications that consume these logs from correctly interpreting the information within them.
This issue affects Apache Log4cxx: before 1.5.0.
Users are recommended to upgrade to version 1.5.0, which fixes the issue.
CVSS Score
6.3
EPSS Score
0.005
Published
2025-08-22
Improper Output Neutralization for Logs vulnerability in Apache Log4cxx.
When using HTMLLayout, logger names are not properly escaped when writing out to the HTML file.
If untrusted data is used to retrieve the name of a logger, an attacker could theoretically inject HTML or Javascript in order to hide information from logs or steal data from the user.
In order to activate this, the following sequence must occur:
* Log4cxx is configured to use HTMLLayout.
* Logger name comes from an untrusted string
* Logger with compromised name logs a message
* User opens the generated HTML log file in their browser, leading to potential XSS
Because logger names are generally constant strings, we assess the impact to users as LOW
This issue affects Apache Log4cxx: before 1.5.0.
Users are recommended to upgrade to version 1.5.0, which fixes the issue.
CVSS Score
2.1
EPSS Score
0.006
Published
2025-08-22