CVE-2020-18652 in exempi
Summary
by MITRE • 08/22/2023
Buffer Overflow vulnerability in WEBP_Support.cpp in exempi 2.5.0 and earlier allows remote attackers to cause a denial of service via opening of crafted webp file.
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Analysis
by VulDB Data Team • 09/06/2025
The CVE-2020-18652 vulnerability represents a critical buffer overflow flaw within the WEBP_Support.cpp component of the exempi library version 2.5.0 and earlier. This vulnerability exists in the handling of WebP image files and presents a significant security risk to systems that process or render such media content. The flaw specifically manifests when the library attempts to parse maliciously crafted WebP files, creating conditions where memory boundaries are exceeded during buffer operations. The vulnerability is classified as a remote code execution risk due to the nature of the buffer overflow, which can potentially be exploited by attackers who control the input data processed by the vulnerable library.
The technical implementation of this vulnerability stems from inadequate bounds checking within the WebP file parsing logic. When the exempi library encounters a specially crafted WebP file, it fails to properly validate the size parameters or structure of the image data, leading to memory corruption. The buffer overflow occurs during the decompression or parsing phase of the WebP format handling, where the library attempts to copy data into fixed-size buffers without sufficient validation of the source data length. This flaw aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios that can occur during dynamic memory allocation. The vulnerability can be triggered through any application or system that utilizes the affected exempi library for WebP image processing, including web browsers, image viewers, and document processing applications.
The operational impact of CVE-2020-18652 extends beyond simple denial of service, as it can potentially enable more sophisticated attack vectors. Remote attackers can leverage this vulnerability to cause application crashes, system instability, or in some cases, achieve arbitrary code execution depending on the specific implementation and memory layout of the target system. The vulnerability affects systems where the exempi library is used for image processing, particularly in environments where users can upload or access WebP files from untrusted sources. This includes web applications, content management systems, and media processing pipelines that handle user-generated content. The attack surface is broad since WebP format support is integrated into many modern applications and browsers, making this vulnerability particularly concerning for organizations maintaining web-facing services or processing untrusted media content.
Mitigation strategies for this vulnerability involve immediate remediation through library updates to versions that contain the patched code. System administrators should prioritize updating the exempi library to version 2.5.1 or later, which includes proper bounds checking and memory validation mechanisms. Additionally, implementing input validation controls at the application level can provide defense-in-depth measures by sanitizing WebP file inputs before processing. Network-level protections such as content filtering and sandboxing mechanisms can help prevent exploitation by limiting the attack surface. The vulnerability demonstrates the importance of proper memory management and input validation practices, aligning with ATT&CK technique T1203, which covers exploitation of software vulnerabilities through buffer overflows. Organizations should also consider implementing automated vulnerability scanning and monitoring systems to detect and respond to similar issues in their software dependencies, as this vulnerability could represent a broader pattern of inadequate input validation in multimedia processing libraries.