CVE-2019-7722 in PMD
Summary
by MITRE
PMD 5.8.1 and earlier processes XML external entities in ruleset files it parses as part of the analysis process, allowing attackers tampering it (either by direct modification or MITM attacks when using remote rulesets) to perform information disclosure, denial of service, or request forgery attacks. (PMD 6.x is unaffected because of a 2017-09-15 change.)
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Analysis
by VulDB Data Team • 07/09/2023
The vulnerability CVE-2019-7722 affects PMD versions 5.8.1 and earlier, exposing a critical security flaw in how the tool handles XML external entity processing during ruleset file parsing. This weakness arises from the software's failure to properly sanitize XML input when analyzing code quality rules, creating an attack surface that can be exploited by malicious actors who gain access to modify ruleset files or intercept network traffic containing remote rulesets. The issue stems from the parser's acceptance of external entity references without proper validation, allowing attackers to craft malicious XML content that can be executed during the analysis process. This vulnerability specifically impacts the XML processing functionality within PMD's rule engine, where external entities are resolved and processed as part of normal operation.
The technical exploitation of this vulnerability enables attackers to perform multiple types of malicious activities through the XML external entity processing mechanism. An attacker who can modify ruleset files or execute man-in-the-middle attacks against remote ruleset downloads can inject malicious XML entities that trigger information disclosure when the parser resolves these entities, potentially exposing sensitive system information or credentials. The vulnerability also enables denial of service attacks by crafting XML entities that cause resource exhaustion or infinite loops during parsing, while request forgery attacks can be executed through entity references that force the parser to make unauthorized network requests to internal systems. This type of vulnerability maps directly to CWE-611, which describes improper restriction of XML external entity processing, and aligns with ATT&CK technique T1059.007 for XML external entity processing.
The operational impact of this vulnerability extends beyond simple code quality analysis, as it can compromise the integrity and security of development environments where PMD is used for automated code review processes. Organizations relying on PMD for security scanning or compliance verification may unknowingly execute malicious code during analysis, potentially leading to data breaches or system compromise. The vulnerability affects both local ruleset files that attackers can modify directly and remote rulesets that are downloaded over unencrypted connections, making it particularly dangerous in environments where network traffic is not properly secured. When combined with other vulnerabilities in development toolchains, this weakness can create a pathway for attackers to escalate privileges or gain unauthorized access to development infrastructure. The fact that PMD 6.x versions are unaffected due to a 2017-09-15 change demonstrates the importance of proper XML security controls in software tooling and the need for regular updates to address emerging threats. Organizations should immediately upgrade to PMD 6.x or later versions to mitigate this risk, while implementing network monitoring to detect potential exploitation attempts and ensuring that all ruleset files are properly validated before use in production environments.