CVE-2018-20099 in Exiv2
Summary
by MITRE
There is an infinite loop in Exiv2::Jp2Image::encodeJp2Header of jp2image.cpp in Exiv2 0.27-RC3. A crafted input will lead to a remote denial of service attack.
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Analysis
by VulDB Data Team • 06/18/2023
The vulnerability identified as CVE-2018-20099 represents a critical denial of service flaw within the Exiv2 image processing library version 0.27-RC3. This library serves as a fundamental component for handling metadata in various image formats including jpeg2000, making it a widely used dependency across numerous applications and systems. The infinite loop occurs within the Exiv2::Jp2Image::encodeJp2Header function located in the jp2image.cpp source file, which demonstrates a classic software design flaw that can be exploited remotely through carefully crafted malicious inputs. The flaw manifests when the library processes specially constructed jpeg2000 image files that trigger an unbounded iterative process within the header encoding routine, causing the application to consume excessive computational resources and eventually become unresponsive.
This vulnerability falls under the category of CWE-835, which specifically addresses the issue of infinite loops in software implementations. The technical nature of the flaw stems from inadequate input validation and boundary checking within the jpeg2000 header processing logic. When an attacker submits a malformed jpeg2000 file that contains manipulated header structures, the encodeJp2Header function enters a condition where loop termination criteria are never met, resulting in continuous execution cycles that can exhaust system resources. The attack vector is particularly concerning as it operates remotely through any application that utilizes Exiv2 for image processing, including web applications, content management systems, and digital asset management platforms. This allows adversaries to potentially disrupt services by consuming CPU cycles and memory resources, effectively creating a denial of service condition that can impact availability of critical systems.
The operational impact of CVE-2018-20099 extends beyond simple service disruption, as it can be leveraged to create cascading effects within larger software ecosystems. Applications that rely on Exiv2 for automatic image processing, such as social media platforms, online photo sharing services, and enterprise document management systems, become vulnerable to sustained denial of service attacks. The vulnerability is particularly dangerous in automated processing environments where applications continuously scan and process uploaded content, as a single malicious file can cause entire processing pipelines to become blocked. From an attacker perspective, the low complexity required to exploit this vulnerability makes it an attractive target for both automated scanning tools and targeted attacks. The flaw demonstrates poor defensive programming practices and highlights the importance of implementing robust input validation mechanisms and resource limiting controls in image processing libraries. The vulnerability can be mapped to ATT&CK technique T1499.004, which covers network denial of service attacks, and T1203, which addresses legitimate user execution through system services, as the exploitation typically occurs through normal application workflows.
Mitigation strategies for CVE-2018-20099 require immediate attention from system administrators and software vendors. The most effective approach involves upgrading to Exiv2 version 0.27 or later, where the infinite loop has been addressed through proper loop boundary validation and input sanitization. Organizations should implement comprehensive input validation measures at the application level, including file size limits, format verification, and timeout mechanisms for image processing operations. Network-level protections can include implementing rate limiting for image uploads and employing sandboxing techniques to isolate image processing operations from critical system resources. Additionally, monitoring systems should be configured to detect unusual CPU consumption patterns that may indicate exploitation attempts. Security teams should also consider implementing automated patch management processes to ensure timely deployment of security updates across all affected systems. The vulnerability underscores the necessity of regular security assessments and code reviews, particularly focusing on iterative constructs and resource-intensive operations within multimedia processing libraries. Organizations that cannot immediately upgrade should consider implementing temporary workarounds such as disabling jpeg2000 format support or implementing strict file validation before processing any uploaded images through Exiv2-dependent applications.