CVE-2015-7558 in librsvg
Summary
by MITRE
librsvg before 2.40.12 allows context-dependent attackers to cause a denial of service (infinite loop, stack consumption, and application crash) via cyclic references in an SVG document.
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Analysis
by VulDB Data Team • 08/21/2022
The vulnerability identified as CVE-2015-7558 affects the librsvg library version prior to 2.40.12, representing a critical security flaw that enables context-dependent attackers to execute denial of service attacks against applications utilizing this library. This vulnerability specifically targets the processing of Scalable Vector Graphics documents and exploits cyclic references within SVG files to create exploitable conditions. The librsvg library serves as a crucial component for rendering SVG graphics in numerous applications across different operating systems and platforms, making this vulnerability particularly concerning for widespread impact. The vulnerability stems from inadequate handling of recursive or circular references within SVG document structures during the parsing and rendering processes.
The technical flaw manifests when the librsvg library encounters cyclic references in SVG documents, which create infinite loops during the parsing phase of the graphic processing pipeline. These cyclic references occur when SVG elements reference each other in a circular manner, creating a scenario where the parser continuously traverses the same elements without reaching a termination point. The vulnerability exploits the lack of proper cycle detection mechanisms within the library's SVG parser, leading to stack consumption as the recursive parsing operations consume memory resources without bounds. This infinite loop condition causes applications to become unresponsive, eventually resulting in application crashes and complete denial of service for users attempting to view or process affected SVG files.
The operational impact of this vulnerability extends beyond simple application crashes, as it can be leveraged by attackers to consume system resources and potentially cause system instability. When applications utilizing librsvg process maliciously crafted SVG files containing cyclic references, they become vulnerable to resource exhaustion attacks that can affect system performance and availability. The vulnerability affects a broad range of applications that depend on librsvg for SVG rendering, including web browsers, graphic design applications, and document viewers. This creates a significant attack surface where malicious actors can craft SVG documents designed to exploit this weakness, leading to service disruption across multiple software platforms. The vulnerability's context-dependent nature means that exploitation requires specific conditions where the affected applications process SVG content, but the potential for widespread impact remains high due to the library's prevalence.
Mitigation strategies for CVE-2015-7558 primarily involve upgrading to librsvg version 2.40.12 or later, which includes fixes for the cyclic reference handling issues. Organizations should prioritize patching affected systems and applications that rely on this library, particularly those handling untrusted SVG content from external sources. Additional defensive measures include implementing content filtering mechanisms to detect and block SVG files with suspicious cyclic references, as well as employing sandboxing techniques to isolate SVG processing operations. Security teams should also consider monitoring for unusual resource consumption patterns that might indicate exploitation attempts, and implementing proper input validation for SVG content to prevent malicious files from reaching the parsing stage. This vulnerability aligns with CWE-838, which addresses insufficient input validation, and can be mapped to ATT&CK technique T1499.001 for resource exhaustion attacks. The remediation process should include comprehensive testing to ensure that the patched version properly handles all SVG edge cases while maintaining compatibility with legitimate SVG files.