CVE-2011-5326 in imlib2
Summary
by MITRE
imlib2 before 1.4.9 allows remote attackers to cause a denial of service (divide-by-zero error and application crash) by drawing an 2x1 ellipse.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2011-5326 represents a critical denial of service flaw within the imlib2 image processing library version 1.4.8 and earlier. This vulnerability specifically manifests when the library processes certain malformed image data, particularly in the context of drawing geometric shapes such as ellipses. The issue stems from inadequate input validation and error handling mechanisms within the image processing pipeline, creating a scenario where maliciously crafted image data can trigger unexpected application behavior.
The technical flaw occurs when imlib2 attempts to draw a 2x1 ellipse, which triggers a divide-by-zero error in the underlying mathematical calculations used for rendering geometric shapes. This mathematical error occurs during the ellipse drawing algorithm where the library fails to properly validate the dimensions of the ellipse before performing division operations. The vulnerability is classified under CWE-369 as a divide by zero error, which represents a fundamental flaw in input validation and arithmetic operation handling. The flaw exists in the geometric rendering module of imlib2, where the ellipse drawing function does not properly check for edge cases or invalid parameter combinations that could lead to mathematical errors during execution.
The operational impact of this vulnerability extends beyond simple application crashes, as it provides remote attackers with a reliable method to disrupt services that depend on imlib2 for image processing. Systems utilizing imlib2 for web image handling, file conversion services, or any application that accepts user-uploaded images become vulnerable to this attack vector. When exploited, the divide-by-zero error causes the application to crash and terminate, leading to a denial of service condition that can be repeatedly triggered by attackers. The vulnerability is particularly dangerous in web environments where users can upload images, as attackers can craft malicious images that will cause the processing application to crash upon handling the image data, effectively preventing legitimate users from accessing services that depend on image processing functionality.
Mitigation strategies for CVE-2011-5326 focus on upgrading to imlib2 version 1.4.9 or later, which includes patches addressing the divide-by-zero error in ellipse drawing operations. Organizations should also implement input validation measures at the application level, including sanitizing image data before processing and implementing timeouts for image handling operations to prevent prolonged exploitation attempts. Additionally, deploying network-based intrusion detection systems that can identify patterns associated with malicious image uploads may provide early warning of attempted exploitation. The vulnerability demonstrates the importance of robust error handling in mathematical operations and input validation, aligning with ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing application-level sandboxing for image processing tasks to limit the impact of potential exploitation, as the vulnerability can be leveraged in broader attack chains targeting image processing services and web applications that utilize imlib2.