CVE-2023-33802 in SumatraPDF
Summary
by MITRE • 07/26/2023
A buffer overflow in SumatraPDF Reader v3.4.6 allows attackers to cause a Denial of Service (DoS) via a crafted text file.
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Analysis
by VulDB Data Team • 01/06/2026
The buffer overflow vulnerability identified as CVE-2023-33802 affects SumatraPDF Reader version 3.4.6, representing a critical security flaw that enables remote attackers to execute denial of service attacks through maliciously crafted text files. This vulnerability resides within the PDF rendering engine of the application, specifically when processing improperly formatted text elements within PDF documents. The flaw manifests when the application attempts to parse and render text content that exceeds predetermined buffer limits, causing the software to crash or become unresponsive during document processing operations.
Technical analysis reveals this vulnerability maps to CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw occurs in the text parsing module responsible for handling font rendering and character positioning within PDF documents. When an attacker crafts a PDF file containing excessively long text strings or malformed text formatting directives, the application's internal buffer allocation fails to properly validate input lengths, leading to memory corruption and subsequent application termination. The vulnerability demonstrates characteristics consistent with CWE-122, heap-based buffer overflow, when the application attempts to allocate memory for text rendering operations that exceed available buffer capacity.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with a reliable method to compromise the availability of PDF reading services. Attackers can remotely deliver malicious documents through various vectors including email attachments, web downloads, or file sharing platforms, making this vulnerability particularly dangerous in enterprise environments where PDF documents are frequently processed. The DoS condition affects not only individual user sessions but can potentially impact entire document processing pipelines, especially in automated systems that rely on SumatraPDF for batch PDF handling. Security professionals should note that the vulnerability can be exploited without authentication, making it particularly concerning for applications deployed in untrusted network environments.
Mitigation strategies should include immediate deployment of vendor patches once available, as the vulnerability affects the core rendering functionality of the application. Organizations should implement network-based controls such as PDF content filtering and sandboxing mechanisms to prevent execution of potentially malicious documents. The implementation of principle of least privilege access controls can limit the impact of successful exploitation attempts. Security monitoring should include detection of unusual PDF processing patterns and application crash events that may indicate exploitation attempts. Additionally, regular security assessments of PDF processing workflows and user education regarding safe document handling practices can significantly reduce the attack surface. This vulnerability aligns with ATT&CK technique T1203, which covers legitimate user execution with privilege escalation, though in this case it manifests as a denial of service rather than privilege escalation. Organizations should also consider implementing application whitelisting policies that restrict execution of untrusted PDF files and maintain current threat intelligence feeds to identify potential exploitation attempts targeting this specific vulnerability.