CVE-2023-46046 in libminizinc
Summary
by MITRE • 03/27/2024
An issue in MiniZinc before 2.8.0 allows a NULL pointer dereference via ti_expr in a crafted .mzn file. NOTE: this is disputed because there is no common libminizinc use case in which an unattended process is supposed to run forever to process a series of atttacker-controlled .mzn files.
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Analysis
by VulDB Data Team • 11/05/2024
The vulnerability identified as CVE-2023-46046 represents a NULL pointer dereference condition within the MiniZinc constraint modeling language compiler prior to version 2.8.0. This flaw specifically manifests within the ti_expr component of the parser when processing maliciously crafted .mzn files. The issue arises from insufficient input validation and error handling mechanisms that fail to properly validate the structure and content of constraint models before attempting to dereference pointers to memory locations. The vulnerability is categorized under CWE-476 which specifically addresses NULL pointer dereference conditions, making it a fundamental memory safety issue that can lead to application crashes or potentially more severe consequences in certain execution contexts. The affected MiniZinc version demonstrates a critical gap in defensive programming practices where the system does not adequately protect against malformed input that could cause the interpreter to attempt operations on uninitialized or invalid memory references.
The technical exploitation of this vulnerability requires an attacker to craft a specific .mzn file containing malformed expressions that trigger the ti_expr parsing logic to attempt dereferencing a NULL pointer. When the MiniZinc compiler processes such a file, the parser encounters a condition where it expects a valid pointer reference but receives NULL instead, leading to an immediate crash of the application. This behavior aligns with the ATT&CK technique T1203 which involves exploiting software vulnerabilities to cause system instability or denial of service conditions. The vulnerability is particularly concerning in environments where MiniZinc is used to process untrusted input, as it provides a straightforward path to application termination without requiring complex exploitation techniques. The NULL pointer dereference occurs at the parsing level rather than during execution, meaning that the vulnerability can be triggered even before the constraint model is fully analyzed or compiled, making it an early-stage attack vector that can effectively prevent legitimate model processing.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can significantly disrupt automated workflows and continuous integration systems that rely on MiniZinc for constraint solving operations. In enterprise environments where constraint modeling is used for scheduling, resource allocation, or optimization problems, an attacker could potentially cause cascading failures by submitting malicious files that trigger these crashes. The vulnerability's disputed nature stems from the argument that typical libminizinc usage patterns do not involve unattended processes continuously processing attacker-controlled input files, which suggests that the risk may be more limited in real-world deployments. However, this perspective overlooks the possibility of indirect exploitation through web applications or services that interface with MiniZinc, where user-provided constraint models could be processed without adequate sanitization. Organizations using MiniZinc in automated or web-facing contexts should consider this vulnerability as a potential threat to system availability and stability.
Mitigation strategies for CVE-2023-46046 primarily involve upgrading to MiniZinc version 2.8.0 or later, which includes proper input validation and error handling mechanisms that prevent the NULL pointer dereference condition. Additionally, implementing proper input sanitization and validation measures can provide defense-in-depth protection for systems that cannot immediately upgrade their MiniZinc installations. Organizations should also consider deploying automated monitoring and alerting systems to detect unusual application crash patterns that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date software components and implementing comprehensive security testing practices that include static analysis and dynamic testing of input processing logic. Security teams should also review their deployment architectures to ensure that constraint modeling systems are not exposed to untrusted input without proper sanitization layers, particularly in cloud environments where automated processing of user-generated content is common.