CVE-2026-117926 in Firefox
Summary
by MITRE • 10/27/2026
Incorrect boundary conditions in the SVG component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security issue stems from incorrect boundary condition handling within the Scalable Vector Graphics rendering engine of Mozilla Firefox. SVG files are XML-based vector image formats that allow for complex graphical definitions including paths, shapes, and transformations. When a browser processes an SVG document, it must parse various attributes such as coordinates, dimensions, and transformation matrices to correctly render the visual output on screen. In this specific instance, the underlying code failed to properly validate or clamp numerical values associated with these geometric properties before performing calculations or memory allocations. This lack of rigorous input validation creates a scenario where maliciously crafted SVG content can trigger unexpected behavior within the rendering pipeline.
From a technical perspective, boundary condition errors often manifest as out-of-bounds reads or writes when indices exceed allocated array limits, or as integer overflows that result in incorrect size calculations for memory buffers. In the context of browser engines like Gecko, which powers Firefox, such flaws can lead to heap corruption if the application attempts to write data beyond the boundaries of a pre-allocated buffer. This type of vulnerability is frequently categorized under CWE-190 Integer Overflow or Wraparound and CWE-787 Out-of-bounds Write depending on the specific manifestation within the codebase. The flaw allows an attacker who can trick a user into loading a specially constructed SVG file to potentially execute arbitrary code with the privileges of the browser process, thereby compromising the integrity and confidentiality of the system hosting the application.
The operational impact of this vulnerability is significant because it affects users browsing web pages that embed or link to maliciously crafted SVG images. Attackers can host these files on compromised websites or distribute them via phishing campaigns. When a victim visits such a page, the browser automatically parses the SVG content during rendering. If the boundary condition flaw is successfully exploited, it may lead to a crash causing denial of service against the user's session, or more critically, allow for remote code execution. This undermines the security model that browsers rely on to isolate web content from the host operating system. The risk is heightened by the ubiquity of SVG in modern web design and its use in data URIs which can be embedded directly within HTML without requiring separate network requests.
Mitigation strategies primarily involve updating the browser software to versions where this logic has been corrected. Mozilla addressed this issue in Firefox version 159, as well as in long-term support releases including Firefox ESR 115.44 and Firefox ESR 153.6. Users should ensure their browsers are updated to these patched versions immediately to eliminate the attack surface associated with SVG parsing errors. Additionally, organizations can implement content security policies that restrict the loading of external resources or disable JavaScript execution in untrusted contexts to reduce the likelihood of exploitation chains being completed. Security awareness training for end-users regarding suspicious links and attachments remains a complementary defense layer against social engineering tactics used to deliver such exploits.
This vulnerability aligns with ATT&CK technique T1204 User Execution, where an adversary relies on user interaction to trigger code execution. It also relates to CWE-798 Use of Hard-coded Credentials if the boundary check was bypassed due to hardcoded limits that were insufficient for certain inputs, although in this case it is more accurately described as a logic error in dynamic bounds checking. The fix ensures that all coordinate and dimension values are properly validated against expected ranges before being passed to lower-level rendering functions. This prevents malformed data from causing memory corruption or logical errors within the graphics subsystem. Maintaining up-to-date software versions is critical for protecting against such low-level implementation flaws that can have high-severity consequences when combined with other vulnerabilities in a browser environment.