CVE-2020-36024 in Poppler
Summary
by MITRE • 08/11/2023
An issue was discovered in freedesktop poppler version 20.12.1, allows remote attackers to cause a denial of service (DoS) via crafted .pdf file to FoFiType1C::convertToType1 function.
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Analysis
by VulDB Data Team • 05/08/2025
The vulnerability identified as CVE-2020-36024 represents a critical denial of service flaw within the freedesktop poppler library version 20.12.1. This library serves as a fundamental component for PDF rendering and processing across numerous operating systems and applications, making the vulnerability particularly concerning from a security perspective. The issue manifests when the FoFiType1C::convertToType1 function processes maliciously crafted pdf files, leading to system instability and potential service interruption. The vulnerability falls under the category of improper input validation, where the library fails to adequately sanitize or validate input data during the conversion process of Type1C font formats to Type1 formats.
The technical exploitation of this vulnerability occurs through the manipulation of specific font data within pdf documents, particularly targeting the Type1C font format conversion mechanism. When a malicious pdf file containing crafted font data is processed by the vulnerable poppler library, the FoFiType1C::convertToType1 function encounters malformed input that triggers an unexpected behavior in the library's memory management or control flow. This typically results in a crash or infinite loop within the application that utilizes poppler for pdf processing, effectively rendering the service unavailable to legitimate users. The flaw demonstrates characteristics consistent with a buffer over-read or memory corruption issue, where the conversion function does not properly validate the boundaries of font data structures, leading to unpredictable execution paths.
From an operational standpoint, this vulnerability presents significant risk to organizations that rely on poppler-based pdf processing systems, including web applications, document management systems, email servers, and print services. The remote nature of the attack means that adversaries can exploit this vulnerability without requiring physical access to the target system, making it particularly dangerous in environments where pdf files are processed automatically or through user interaction. The impact extends beyond simple service disruption to potentially enable more sophisticated attacks, as the DoS condition can be used as a precursor to other exploitation techniques or as a means to exhaust system resources and cause broader operational degradation. This vulnerability particularly affects systems where pdf processing is automated or where users can upload or receive pdf documents from untrusted sources.
Mitigation strategies for CVE-2020-36024 should prioritize immediate patching of affected poppler installations to version 20.12.2 or later, which contains the necessary fixes for the font conversion function. Organizations should implement additional defensive measures including pdf file validation and sanitization before processing, network-based filtering to block suspicious pdf content, and monitoring for unusual resource consumption patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and can be mapped to ATT&CK technique T1499.004 for network denial of service attacks. Security teams should also consider implementing application whitelisting controls and restricting pdf processing capabilities in high-risk environments to minimize the attack surface and reduce the potential impact of successful exploitation attempts.