CVE-2023-27586 in CairoSVG
Summary
by MITRE • 03/20/2023
CairoSVG is an SVG converter based on Cairo, a 2D graphics library. Prior to version 2.7.0, Cairo can send requests to external hosts when processing SVG files. A malicious actor could send a specially crafted SVG file that allows them to perform a server-side request forgery or denial of service. Version 2.7.0 disables CairoSVG's ability to access other files online by default.
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Analysis
by VulDB Data Team • 04/12/2023
CairoSVG represents a significant security vulnerability through its exposure to server-side request forgery attacks, with CVE-2023-27586 highlighting a critical flaw in the SVG processing pipeline. This vulnerability affects versions prior to 2.7.0 where the underlying Cairo graphics library could be coerced into establishing outbound network connections when processing untrusted SVG content. The flaw arises from insufficient input validation and network access controls within the SVG parsing mechanism, allowing attackers to craft malicious SVG files that trigger unintended network behavior. The vulnerability operates at the intersection of web application security and graphics processing, creating a unique attack surface where document rendering becomes a vector for network-based exploitation.
The technical implementation of this vulnerability stems from CairoSVG's default configuration that permits external resource resolution during SVG processing. When an attacker submits a malicious SVG file, the parser may attempt to fetch external resources such as images, stylesheets, or other referenced elements, effectively enabling a server-side request forgery attack. This behavior can be leveraged to probe internal networks, exfiltrate data, or perform denial of service attacks against external systems. The vulnerability directly maps to CWE-918, which describes server-side request forgery vulnerabilities, and can be categorized under ATT&CK technique T1190 for exploitation through web applications. The flaw manifests when the SVG parser encounters external references without proper sandboxing or access controls, creating a pathway for unauthorized network communication.
The operational impact of this vulnerability extends beyond simple exploitation to encompass potential data breaches and service disruption. Attackers could leverage the vulnerability to access internal resources that would normally be isolated from external networks, potentially exposing sensitive systems or data. The denial of service component of this vulnerability could be exploited by submitting SVG files designed to cause the application to hang or consume excessive resources while attempting to resolve external references. Organizations relying on CairoSVG for document conversion or rendering may face significant security risks, particularly in environments where SVG processing occurs on behalf of untrusted users or external parties. The vulnerability affects both web applications and server-side processing environments where SVG files are converted to other formats.
Mitigation strategies for CVE-2023-27586 center on upgrading to CairoSVG version 2.7.0 or later, where the default configuration disables external network access during SVG processing. Organizations should implement additional security measures including network segmentation, firewall rules to restrict outbound connections, and comprehensive input validation for all SVG content. The vulnerability can be addressed through proper sandboxing of SVG processing environments, implementing strict access controls for external resources, and conducting regular security assessments of SVG handling components. Security teams should also consider implementing monitoring solutions to detect anomalous network activity during SVG processing, as this can serve as an early warning indicator of exploitation attempts. The fix implemented in version 2.7.0 represents a defensive programming approach that aligns with security best practices for preventing unintended network access during document processing operations.