CVE-2026-113399 in Firefox
Summary
by MITRE • 10/20/2026
Incorrect boundary conditions in the SVG component. This vulnerability was fixed in Firefox 158.0.1.
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Analysis
by VulDB Data Team • 10/20/2026
The identified security issue resides within the Scalable Vector Graphics, or SVG, rendering engine of Mozilla Firefox, specifically involving incorrect handling of boundary conditions during the processing of vector graphic data. SVG is an XML-based markup language used to define two-dimensional vector graphics for web applications, and its complexity allows for a wide variety of visual elements that must be accurately parsed and rendered by the browser's layout engine. When the parser encounters specific edge cases or malformed input where coordinate boundaries are not strictly validated against expected limits, it can lead to memory corruption vulnerabilities such as buffer overflows or out-of-bounds reads. These types of flaws typically arise when internal calculations for clipping paths, transformations, or path intersections fail to account for extreme values that exceed the allocated memory buffers or logical constraints defined by the rendering specification.
From a technical perspective, this vulnerability represents a classic instance of improper input validation leading to potential exploitation through crafted SVG files embedded in web pages or loaded locally. An attacker could construct a malicious document containing specially designed vector data with boundary conditions that trigger the flawed logic within the parser. If successfully exploited, such an error can allow for arbitrary code execution on the victim's system by overwriting memory structures or executing shellcode placed in accessible memory regions. This aligns closely with Common Weakness Enumeration category CWE-120, which describes buffer copy without checking size limits, and potentially CWE-787, regarding out-of-bounds write access. The severity of this flaw is heightened because SVG parsing often occurs during the initial loading phase of a webpage, providing an early attack surface before many other security controls are fully engaged.
The operational impact of this vulnerability extends beyond simple application crashes to significant risks involving data exfiltration and full system compromise. Since Firefox processes these graphics as part of normal browsing activities, users visiting compromised websites or opening malicious attachments containing the crafted SVG files could inadvertently trigger the exploit without any additional interaction required from them in some scenarios. This lack of user intervention makes it particularly dangerous for targeted attacks where stealth is paramount. Furthermore, because modern browsers operate with sandboxing mechanisms to limit the damage of such exploits, successful exploitation might still be constrained by these protections; however, attackers frequently chain multiple vulnerabilities together to escape sandboxes and achieve higher privileges on the host operating system.
To mitigate this risk, users must ensure that their browser is updated to version 158.0.1 or later, as Mozilla has released a patch addressing the boundary condition checks within the SVG component. This update likely involves stricter validation of coordinate values during parsing and enhanced bounds checking before memory allocation operations are performed on graphic elements. Organizations should enforce automated patch management policies to ensure all endpoints running Firefox remain current with security updates. Additionally, implementing content security policies that restrict the loading of external scripts or untrusted resources can reduce the attack surface presented by malicious web pages attempting to leverage this flaw. Security teams should also monitor for indicators of compromise related to SVG parsing anomalies in network traffic logs and endpoint detection systems to identify potential exploitation attempts before they result in successful breaches.