CVE-2021-36089 in Grok
Summary
by MITRE • 07/01/2021
Grok 7.6.6 through 9.2.0 has a heap-based buffer overflow in grk::FileFormatDecompress::apply_palette_clr (called from grk::FileFormatDecompress::applyColour).
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Analysis
by VulDB Data Team • 07/04/2021
The vulnerability identified as CVE-2021-36089 represents a critical heap-based buffer overflow within the Grok image processing library version ranges 7.6.6 through 9.2.0. This flaw resides in the grk::FileFormatDecompress::apply_palette_clr function which is invoked by the grk::FileFormatDecompress::applyColour method, creating a chain of function calls that ultimately leads to memory corruption. The issue stems from insufficient input validation and bounds checking when processing color palette data within image files, particularly affecting JPEG 2000 format handling. The vulnerability manifests when the library processes malformed or specially crafted image files that contain oversized palette data, causing the application to write beyond allocated memory boundaries.
This heap-based buffer overflow presents significant operational risks as it can be exploited to achieve arbitrary code execution or system compromise. The vulnerability falls under CWE-121, heap-based buffer overflow, which is classified as a critical weakness in the Common Weakness Enumeration catalog. Attackers can leverage this flaw by crafting malicious image files that trigger the vulnerable code path, potentially leading to remote code execution on systems that process these images through the affected Grok library. The exploitation requires no special privileges and can be executed through standard file processing operations, making it particularly dangerous in web applications, content management systems, or any environment where user-uploaded images are processed.
The impact of this vulnerability extends across multiple operational domains including web applications, image processing servers, and content delivery networks that utilize the Grok library for JPEG 2000 image handling. Organizations using affected versions face potential data breaches, system compromise, and denial of service conditions when processing untrusted image content. The vulnerability is particularly concerning in cloud environments where image processing services may be exposed to untrusted inputs from multiple sources. From an ATT&CK framework perspective, this vulnerability maps to T1203, Exploitation for Client Execution, and T1059, Command and Scripting Interpreter, as successful exploitation could enable attackers to execute arbitrary commands on affected systems.
Mitigation strategies should focus on immediate version upgrades to Grok 9.2.1 or later, which contain the necessary patches to address the buffer overflow condition. Organizations should implement strict input validation and sanitization for all image files processed through the library, including implementing file format validation and size limitations. Network segmentation and access controls should be enforced to limit exposure of systems utilizing the vulnerable library. Additionally, implementing automated monitoring and alerting for suspicious file processing activities can help detect potential exploitation attempts. The vulnerability underscores the importance of regular security updates and proper dependency management in software supply chain security practices, as outlined in NIST SP 800-171 and ISO/IEC 27001 standards for information security management.