CVE-2009-1827 in Firefox
Summary
by MITRE
The SVG component in Mozilla Firefox 3.0.4 allows remote attackers to cause a denial of service (application hang) via a large value in the r (aka Radius) attribute of a circle element, related to an "unclamped loop."
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability described in CVE-2009-1827 represents a critical denial of service weakness within Mozilla Firefox 3.0.4's Scalable Vector Graphics implementation. This flaw specifically targets the processing of circle elements within SVG documents, where the r attribute controls the radius of the circle shape. The vulnerability arises from insufficient input validation and bounds checking in the SVG rendering engine, creating a scenario where maliciously crafted SVG content can trigger unexpected behavior in the browser application. The issue stems from an unclamped loop condition that occurs when processing excessively large radius values, causing the browser to consume excessive computational resources and ultimately hang the application.
The technical execution of this vulnerability involves an attacker constructing an SVG document containing a circle element with an abnormally large r attribute value that exceeds normal processing limits. When Firefox attempts to render this malformed SVG content, the unclamped loop mechanism fails to properly terminate or constrain the processing loop, leading to resource exhaustion and application hang. This represents a classic case of inadequate input sanitization where the system fails to validate the magnitude of user-supplied parameters before processing them. The vulnerability operates at the intersection of web standards implementation and security boundaries, where the legitimate SVG specification feature becomes a vector for exploitation due to poor defensive programming practices.
From an operational impact perspective, this vulnerability significantly compromises the availability and stability of Firefox 3.0.4 installations when processing untrusted SVG content. The denial of service condition affects not only individual user sessions but can also impact broader network availability if exploited in mass mailing campaigns or web-based attack vectors. The vulnerability is particularly concerning because SVG content can be embedded in various web contexts including email attachments, web pages, and web applications, making it difficult to fully mitigate without comprehensive browser updates. This issue demonstrates how seemingly benign web standards features can become security liabilities when proper bounds checking and input validation mechanisms are absent from implementation code.
The vulnerability aligns with CWE-704, which classifies improper input validation as a weakness that occurs when a system fails to properly validate or sanitize input data before processing it. Additionally, this weakness maps to ATT&CK technique T1499.004, which covers "Evasion Through Code Modification" and specifically addresses denial of service attacks that exploit implementation flaws in software components. The lack of proper bounds checking in this case creates a pathway for attackers to consume excessive system resources through controlled input manipulation. Security professionals should note that this vulnerability highlights the importance of defensive programming practices including input validation, resource limiting, and proper loop termination conditions in multimedia and graphics processing components.
Mitigation strategies for CVE-2009-1827 require immediate deployment of Mozilla Firefox 3.0.5 or later versions, which contain the necessary patches to address the unclamped loop condition in SVG processing. Organizations should also implement content filtering mechanisms to restrict SVG content from untrusted sources, particularly in environments where users may encounter malicious web content. Browser security configurations should include enhanced sandboxing and resource monitoring to detect and prevent abnormal resource consumption patterns. Network administrators should consider implementing web application firewalls that can identify and block suspicious SVG content patterns. The vulnerability underscores the necessity of regular security updates and continuous monitoring of software components for implementation flaws that could be exploited in denial of service attacks.