CVE-2020-18839 in poppler
Summary
by MITRE • 08/22/2023
Buffer Overflow vulnerability in HtmlOutputDev::page in poppler 0.75.0 allows attackers to cause a denial of service.
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Analysis
by VulDB Data Team • 09/16/2023
The buffer overflow vulnerability identified as CVE-2020-18839 resides within the HtmlOutputDev::page function of the poppler library version 0.75.0, representing a critical security flaw that enables malicious actors to execute denial of service attacks. This vulnerability stems from insufficient input validation and memory management within the HTML output generation component of the poppler PDF rendering library. The flaw occurs when processing specially crafted PDF documents that contain malformed HTML output data, causing the application to write beyond allocated memory boundaries and potentially leading to application crashes or system instability.
The technical implementation of this vulnerability demonstrates a classic buffer overflow condition where the HtmlOutputDev::page method fails to properly bounds-check input data before copying it into fixed-size memory buffers. When processing PDF files containing maliciously constructed HTML elements, the function attempts to write data that exceeds the predetermined buffer limits, resulting in memory corruption that can trigger segmentation faults or arbitrary code execution depending on the system configuration. This type of vulnerability aligns with CWE-121, which categorizes buffer overflow conditions as weaknesses in memory management, and represents a direct threat to application stability and system integrity.
From an operational perspective, this vulnerability poses significant risks to organizations relying on poppler for PDF processing and rendering operations. Attackers can exploit this flaw by crafting malicious PDF documents that, when processed by applications using the vulnerable poppler version, will cause the target system to crash or become unresponsive. The denial of service impact extends beyond individual applications to potentially affect entire document processing pipelines, web services, and automated workflows that depend on PDF rendering capabilities. This vulnerability particularly affects systems where poppler is integrated into web applications, document management systems, and security scanning tools that process untrusted PDF content.
The mitigation strategies for CVE-2020-18839 involve immediate upgrading to poppler versions that contain patches addressing this buffer overflow condition, typically poppler 0.76.0 or later releases that include proper bounds checking and memory management improvements. System administrators should also implement input validation measures at the application level, including PDF content sanitization and sandboxing techniques to isolate vulnerable processing components. Additionally, network-level protections such as web application firewalls and content filtering systems can help detect and prevent exploitation attempts. Organizations should conduct comprehensive vulnerability assessments to identify all systems utilizing vulnerable poppler versions and establish monitoring protocols to detect potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004, which covers network denial of service attacks, and T1059.007, representing command and scripting interpreter usage, as attackers may leverage this flaw to disrupt system availability through controlled resource exhaustion and memory corruption techniques.