A flaw was found in the Apache Log4j logging library 2.x. when the logging configuration uses a non-default Pattern Layout with a Context Lookup. Attackers with control over Thread Context Map (MDC) input data can craft malicious input data that contains a recursive lookup and can cause Denial of Service.

A flaw was found in dom4j library. By using the default SaxReader() provided by Dom4J, external DTDs and External Entities are allowed, resulting in a possible XXE.

A flaw was found in the Apache Xerces Java (XercesJ) XML parser when handling specially crafted XML document payloads. This issue causes the XercesJ XML parser to wait in an infinite loop, which may consume system resources for a prolonged duration, leading to a denial of service condition.

Apache Ant is vulnerable to a denial of service, caused by an out-of-memory error when large amounts of memory are allocated. By persuading a victim to open a specially-crafted ZIP archive, a remote attacker could exploit this vulnerability to cause the application to crash.

In Apache Commons IO before 2.7, When invoking the method FileNameUtils.normalize with an improper input string, like "//../foo", or "\\..\foo", the result would be the same value, thus possibly providing access to files in the parent directory, but not further above (thus "limited" path traversal), if the calling code would use the result to construct a path value.

References:

https://www.openwall.com/lists/oss-security/2021/04/12/1 https://issues.apache.org/jira/browse/IO-556

Apache Log4j is vulnerable to a man-in-the-middle attack, caused by improper certificate validation with host mismatch in the SMTP appender. An attacker could exploit this vulnerability to launch a man-in-the-middle attack and gain access to the communication channel between endpoints to obtain sensitive information or further compromise the system.