CVE-2022-24191 in htmldoc
Summary
by MITRE • 04/04/2022
In HTMLDOC 1.9.14, an infinite loop in the gif_read_lzw function can lead to a pointer arbitrarily pointing to heap memory and resulting in a buffer overflow.
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Analysis
by VulDB Data Team • 05/01/2025
The vulnerability identified as CVE-2022-24191 resides within HTMLDOC version 1.9.14, a widely used document processing library that converts html documents to pdf and other formats. This flaw manifests as an infinite loop within the gif_read_lzw function, which is responsible for reading and decompressing lzw compressed data streams from gif image files. The infinite loop occurs when processing malformed gif files that contain invalid lzw compression parameters, causing the decompression routine to enter a state where it continuously iterates without proper termination conditions. This fundamental flaw in the decompression algorithm creates a critical security risk that extends beyond simple denial of service.
The technical implementation of this vulnerability demonstrates a classic buffer overflow condition that arises from improper bounds checking during lzw decompression. When the gif_read_lzw function encounters malformed input data, the infinite loop causes the decompression algorithm to consume excessive memory resources while maintaining pointers that eventually point to arbitrary heap memory locations. This heap pointer corruption directly enables an attacker to manipulate memory contents and potentially execute arbitrary code through memory corruption techniques. The vulnerability operates under CWE-835 which specifically addresses infinite loops that can lead to memory corruption, while also aligning with ATT&CK technique T1203 for legitimate program execution and T1059 for command and scripting interpreter usage in exploitation scenarios.
The operational impact of CVE-2022-24191 extends significantly beyond traditional denial of service attacks, as it provides potential for remote code execution in systems that process untrusted gif files through HTMLDOC. Applications utilizing this library for document conversion, web content processing, or file upload validation become vulnerable to exploitation when handling maliciously crafted gif files. The vulnerability is particularly concerning in web applications, content management systems, and document processing services that automatically convert user-uploaded files to pdf or other formats. Attackers could leverage this flaw to execute arbitrary code on affected systems, potentially leading to complete system compromise and unauthorized access to sensitive data. The heap memory corruption aspect of this vulnerability makes it especially dangerous as it can be exploited to bypass modern memory protection mechanisms.
Mitigation strategies for CVE-2022-24191 require immediate patching of HTMLDOC to version 1.9.15 or later, which contains the fixed gif_read_lzw implementation with proper loop termination and bounds checking. Organizations should implement strict input validation for all gif files processed through HTMLDOC, including size limitations and format verification before decompression. Network-level protections can include content filtering appliances that scan for malformed gif files and prevent their processing through vulnerable systems. Additionally, deploying application sandboxing techniques and memory protection mechanisms such as stack canaries, address space layout randomization, and data execution prevention can help mitigate exploitation attempts. Security monitoring should focus on detecting unusual memory consumption patterns and potential buffer overflow indicators during document processing operations. The vulnerability serves as a reminder of the critical importance of proper input validation and bounds checking in decompression algorithms, particularly in widely deployed libraries that process untrusted data from external sources.