CVE-2018-9145 in Exiv2
Summary
by MITRE
In Exiv2 0.26, there is a reachable assertion abort in the function Exiv2::DataBuf::DataBuf at include/exiv2/types.hpp.
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Analysis
by VulDB Data Team • 01/18/2020
The vulnerability identified as CVE-2018-9145 represents a critical software flaw within the Exiv2 library version 0.26, specifically manifesting as a reachable assertion abort within the Exiv2::DataBuf::DataBuf function located in the include/exiv2/types.hpp file. This issue arises from inadequate input validation and error handling mechanisms that fail to properly process malformed or unexpected data structures. The flaw occurs during the initialization of data buffer objects, where the assertion mechanism triggers an abrupt program termination rather than gracefully handling the malformed input. Such behavior creates a potential denial of service condition that can be exploited by malicious actors who craft specially formatted input data to trigger the assertion failure.
This vulnerability falls under the category of assertion failure and can be categorized as CWE-617, which specifically addresses reachable assertions that can be triggered by external input. The technical implementation flaw stems from the library's failure to validate buffer size parameters and data integrity checks during object construction. When the DataBuf constructor encounters unexpected input parameters or corrupted data structures, the assertion mechanism designed for debugging purposes becomes exploitable in production environments. The assertion abort occurs at a fundamental level within the library's memory management system, affecting any application that relies on Exiv2 for image metadata processing, particularly those handling untrusted image files from external sources.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially compromise the stability and reliability of applications that depend on Exiv2. Attackers can craft malicious image files that, when processed by vulnerable applications, trigger the assertion abort and cause the application to crash or terminate unexpectedly. This creates a significant risk for web applications, content management systems, and digital asset management platforms that process user-uploaded images. The vulnerability is particularly dangerous in server environments where continuous availability is critical, as a single malicious file can cause service disruption. Additionally, the crash behavior may provide attackers with opportunities to perform further exploitation attempts or gather information about the system's internal state.
Mitigation strategies for CVE-2018-9145 should prioritize immediate patching of affected Exiv2 versions to the latest stable releases that contain the necessary fixes for the assertion handling mechanism. Organizations should implement comprehensive input validation and sanitization procedures for all image files processed through Exiv2, particularly those originating from untrusted sources. The recommended approach includes deploying application-level defenses such as sandboxing mechanisms, memory protection boundaries, and robust error handling that prevents assertion failures from cascading into application crashes. Security teams should also consider implementing monitoring and alerting systems to detect unusual crash patterns or service disruptions that may indicate exploitation attempts. Additionally, the ATT&CK framework categorizes this vulnerability under the T1499.004 technique for network denial of service, emphasizing the importance of proper input validation and the need for resilient error handling in software libraries. Organizations should conduct thorough vulnerability assessments to identify all applications using the vulnerable Exiv2 version and ensure proper remediation through updated library versions or alternative implementations that maintain the necessary functionality while eliminating the exploitable assertion failure.