CVE-2019-11023 in Graphviz
Summary
by MITRE
The agroot() function in cgraph\obj.c in libcgraph.a in Graphviz 2.39.20160612.1140 has a NULL pointer dereference, as demonstrated by graphml2gv.
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Analysis
by VulDB Data Team • 08/27/2023
The vulnerability identified as CVE-2019-11023 resides within the Graphviz software suite, specifically in the libcgraph.a library version 2.39.20160612.1140. This issue manifests in the agroot() function located within the cgraph\obj.c source file, representing a critical NULL pointer dereference flaw that can be exploited through the graphml2gv utility. The vulnerability occurs when processing certain GraphML formatted input files, creating a scenario where the application attempts to dereference a null pointer during the graph root node retrieval process. This flaw represents a classic denial of service vulnerability that can be triggered remotely by an attacker who controls the input data processed by the affected software component.
The technical nature of this vulnerability stems from inadequate input validation and error handling within the agroot() function implementation. When graphml2gv processes malformed or specially crafted GraphML files, the function fails to properly check for null return values from internal operations that should provide valid graph root node references. This null pointer dereference occurs because the software assumes certain internal data structures will always contain valid references, without implementing proper null checks before accessing memory locations. The flaw directly maps to CWE-476, which specifically addresses NULL pointer dereference conditions, and represents a fundamental failure in defensive programming practices that should be implemented in all software components handling external input data.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can be leveraged in broader attack vectors within software supply chain contexts. Attackers who can influence the input processed by Graphviz applications, particularly in automated workflows or web applications that convert GraphML to other formats, can trigger this vulnerability to cause application crashes or system instability. This becomes particularly concerning in environments where Graphviz is used as part of automated build processes, documentation generation pipelines, or web-based graph visualization services. The vulnerability can be exploited in scenarios where untrusted GraphML input is processed without proper sanitization, potentially allowing for service disruption or even system compromise if the application is running with elevated privileges.
Mitigation strategies for CVE-2019-11023 should focus on immediate software updates to patched versions of Graphviz where the NULL pointer dereference has been addressed through proper input validation and error handling. Organizations should implement strict input validation measures for any GraphML files processed by Graphviz applications, including sanitization routines that can detect and reject malformed input before it reaches the vulnerable code paths. Security teams should consider implementing network segmentation and access controls to limit exposure of Graphviz applications to untrusted input sources, while also establishing monitoring procedures to detect potential exploitation attempts. The remediation efforts align with ATT&CK technique T1499.004, which addresses the exploitation of vulnerabilities in software libraries, and organizations should prioritize patch management processes to ensure all instances of Graphviz within their infrastructure are updated to versions that address this specific NULL pointer dereference vulnerability.