CVE-2012-5340 in SumatraPDF
Summary
by MITRE
SumatraPDF 2.1.1/MuPDF 1.0 allows remote attackers to cause an Integer Overflow in the lex_number() function via a corrupt PDF file.
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Analysis
by VulDB Data Team • 04/27/2025
The vulnerability identified as CVE-2012-5340 represents a critical integer overflow flaw affecting SumatraPDF version 2.1.1 when integrated with MuPDF version 1.0. This issue manifests within the lex_number() function, which is responsible for parsing numeric values during PDF document processing. The vulnerability arises from insufficient input validation and improper handling of integer arithmetic operations when processing malformed PDF content. Attackers can exploit this weakness by crafting specially designed corrupt PDF files that trigger the overflow condition during document parsing, potentially leading to unpredictable behavior and system instability.
The technical exploitation of this vulnerability occurs through the manipulation of numeric values within PDF streams or objects that are processed by the lex_number() function. When MuPDF attempts to parse malformed numeric data, the integer overflow can result in memory corruption, buffer overflows, or arbitrary code execution depending on the specific implementation details and system configuration. This type of vulnerability falls under CWE-190, which specifically addresses integer overflow conditions that can lead to memory corruption and potential privilege escalation. The flaw demonstrates a classic case of inadequate bounds checking in parsing operations, where the system fails to properly validate the range of integer values before performing arithmetic operations.
The operational impact of CVE-2012-5340 extends beyond simple denial of service scenarios, as it can potentially enable remote code execution attacks. When a victim opens a maliciously crafted PDF document, the vulnerable parsing routine can be triggered, causing the application to behave unpredictably and potentially allowing attackers to execute arbitrary code with the privileges of the running process. This vulnerability affects the broader PDF processing ecosystem and demonstrates how seemingly minor parsing flaws in document rendering libraries can have significant security implications. The attack vector is particularly concerning as it requires no special privileges or user interaction beyond opening the malicious document, making it a prime target for phishing campaigns and targeted attacks against unsuspecting users.
Mitigation strategies for CVE-2012-5340 should focus on immediate patching of affected systems and implementation of defensive measures. Organizations should prioritize updating to patched versions of SumatraPDF and MuPDF that address the integer overflow condition in the lex_number() function. Additionally, implementing sandboxing techniques and restricting PDF file execution in restricted environments can provide additional layers of protection. Security controls should include monitoring for unusual parsing behavior and implementing strict input validation for all PDF content. From an ATT&CK framework perspective, this vulnerability maps to techniques involving execution through libraries and privilege escalation, emphasizing the need for comprehensive security measures that address both the immediate flaw and potential exploitation pathways. Regular security assessments and vulnerability scanning should be conducted to identify similar issues in other document processing components and ensure overall system resilience against similar attack vectors.