CVE-2020-36331 in iOS
Summary
by MITRE • 05/21/2021
A flaw was found in libwebp in versions before 1.0.1. An out-of-bounds read was found in function ChunkAssignData. The highest threat from this vulnerability is to data confidentiality and to the service availability.
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Analysis
by VulDB Data Team • 07/27/2021
The vulnerability identified as CVE-2020-36331 represents a critical out-of-bounds read flaw within the libwebp library version 1.0.1 and earlier. This issue specifically manifests in the ChunkAssignData function where improper bounds checking allows maliciously crafted webp image files to trigger memory access violations. The flaw originates from insufficient input validation mechanisms that fail to properly verify the boundaries of data structures during image processing operations. When an attacker submits a malformed webp file containing crafted metadata or image data, the library attempts to read memory locations beyond the allocated buffer boundaries, potentially exposing sensitive information or causing application crashes.
This vulnerability operates at the intersection of memory safety and image processing security, creating significant risks for systems that process untrusted webp content. The out-of-bounds read condition can lead to information disclosure through memory leaks that might reveal sensitive data from adjacent memory regions, while also potentially causing denial of service through application crashes or system instability. The vulnerability's impact extends beyond simple data corruption as it can be exploited in scenarios where webp images are processed automatically without proper sanitization, such as in web applications, content management systems, or image processing pipelines. According to CWE classification, this represents a CWE-125: Out-of-bounds Read vulnerability, which is categorized under the broader weakness of improper validation of bounds of a buffer.
The operational implications of CVE-2020-36331 are particularly severe in environments where webp image processing is a common operation, as it can be leveraged for both information disclosure and availability attacks. Attackers can craft malicious webp files that trigger the vulnerability during normal image processing workflows, potentially leading to data breaches or service disruption. The threat model aligns with ATT&CK technique T1203: Exploitation for Client Execution, where adversaries exploit software vulnerabilities to execute malicious code or cause system instability. Systems utilizing libwebp for image handling, including web servers, mobile applications, and image processing frameworks, become vulnerable to remote exploitation when they process untrusted input without proper validation.
Mitigation strategies for this vulnerability require immediate patching of libwebp to version 1.0.1 or later where the out-of-bounds read has been addressed through proper bounds checking implementation. Organizations should implement input validation measures that sanitize all webp image content before processing, including verifying file headers, metadata structures, and image dimensions against expected parameters. Network-level protections such as web application firewalls can be configured to detect and block suspicious webp file patterns, while runtime monitoring systems should be deployed to detect anomalous memory access patterns that may indicate exploitation attempts. Additionally, implementing sandboxing mechanisms for image processing operations and maintaining up-to-date security patches for all dependencies will provide layered protection against similar vulnerabilities in the future.