CVE-2020-19716 in Exiv2
Summary
by MITRE • 07/14/2021
A buffer overflow vulnerability in the Databuf function in types.cpp of Exiv2 v0.27.1 leads to a denial of service (DOS).
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Analysis
by VulDB Data Team • 07/18/2021
The buffer overflow vulnerability identified as CVE-2020-19716 resides within the Exiv2 library version 0.27.1, specifically within the Databuf function located in the types.cpp source file. This vulnerability represents a critical security flaw that can be exploited to cause denial of service conditions within applications that rely on Exiv2 for image metadata processing. The flaw manifests when the library processes malformed image files containing specially crafted metadata that triggers an improper buffer handling scenario during the data buffer allocation process. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, indicating that the flaw occurs when insufficient bounds checking allows data to be written beyond the allocated buffer boundaries. This particular implementation issue affects the library's ability to safely process image files, creating a scenario where maliciously crafted inputs can cause the application to crash or become unresponsive.
The technical exploitation of this vulnerability occurs when an application using Exiv2 attempts to read metadata from an image file that contains malformed data structures within its metadata sections. During the processing of such files, the Databuf function fails to properly validate input parameters before performing buffer operations, leading to memory corruption that results in program termination. The flaw specifically impacts the library's handling of image metadata parsing, where it attempts to allocate or resize buffers without adequate boundary checks, allowing attackers to manipulate the buffer size calculations through crafted input data. This type of vulnerability falls under the ATT&CK technique T1499.004 for Network Denial of Service, as it can be leveraged to disrupt services through controlled input manipulation. The vulnerability's impact extends beyond simple application crashes to potentially enable more sophisticated attack vectors if combined with other exploitation techniques, particularly in environments where Exiv2 is used for processing untrusted image content.
The operational impact of CVE-2020-19716 extends to any system or application that integrates Exiv2 for image metadata processing, including but not limited to content management systems, digital asset management platforms, photo editing applications, and web services that handle user-uploaded images. Organizations relying on Exiv2 for image processing workflows face significant risk of service disruption, as attackers can craft malicious image files that will cause the vulnerable applications to crash when attempting to process them. This denial of service condition can be particularly damaging in high-availability environments where continuous service availability is critical, as it may require system restarts or manual intervention to restore normal operations. The vulnerability is especially concerning in web applications that accept image uploads, as it can be exploited to create persistent service disruption attacks that degrade system performance or completely prevent legitimate users from accessing services. The flaw's exploitation requires minimal technical skill and can be automated, making it a particularly attractive target for malicious actors seeking to disrupt services.
Mitigation strategies for CVE-2020-19716 should prioritize immediate patching of Exiv2 libraries to version 0.27.2 or later, which contains the necessary fixes for the buffer overflow condition. System administrators should conduct comprehensive vulnerability assessments to identify all applications and services that utilize Exiv2, ensuring that all instances are updated to prevent exploitation. Additional protective measures include implementing input validation and sanitization for image files before processing, deploying network monitoring solutions to detect unusual patterns in image processing requests, and establishing robust error handling procedures that can gracefully manage malformed input data. Organizations should also consider implementing application sandboxing techniques to limit the impact of potential exploitation, ensuring that even if a vulnerability is successfully exploited, the damage remains contained. Regular security updates and patch management procedures should be strengthened to prevent similar vulnerabilities from being introduced in other components of the system architecture. The vulnerability demonstrates the importance of thorough code review processes, particularly for libraries handling user-provided data, and highlights the need for implementing comprehensive testing procedures including fuzzing and boundary condition testing to identify potential buffer overflow scenarios before they can be exploited in production environments.