CVE-2026-109730 in Firefox
Summary
by MITRE • 10/13/2026
Integer overflow in the Graphics component. This vulnerability was fixed in Firefox 158, Firefox ESR 115.43, and Firefox ESR 153.5.
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Analysis
by VulDB Data Team • 10/14/2026
The identified security issue represents a critical integer overflow condition located within the graphics subsystem of Mozilla Firefox browsers. Integer overflows occur when an arithmetic operation results in a value that exceeds the maximum limit for the data type used to store it, causing the value to wrap around or truncate unexpectedly. In this specific instance, the flaw resides in how memory allocation sizes are calculated during rendering operations. When processing complex graphical elements such as SVG paths, canvas drawings, or WebGL contexts, the browser may compute a buffer size based on user-supplied input or internal state variables without adequate bounds checking. If these calculations involve multiplication of large values that exceed the capacity of a 32-bit integer, the resulting allocated memory block will be significantly smaller than intended by subsequent operations expecting to write data into it.
This technical flaw creates a high-risk scenario for heap-based buffer overflows or out-of-bounds writes. When the graphics engine proceeds with rendering tasks assuming sufficient memory space has been reserved based on the flawed calculation, actual write operations can spill beyond the boundaries of the allocated heap region. This corruption affects adjacent memory structures which may contain critical control data such as function pointers, object headers, or other metadata used by the JavaScript engine and browser internals. The exploitation potential is severe because it allows an attacker to achieve arbitrary code execution with the privileges of the victim user. By carefully crafting malicious web content that triggers this overflow during rendering, a threat actor can overwrite memory in a way that redirects program flow to shellcode injected into the process space, effectively bypassing modern browser security mitigations like ASLR and DEP if not properly configured or circumvented through additional techniques.
From an industry standard perspective, this vulnerability aligns with CWE-190 Integer Overflow or Wraparound and often leads directly to CWE-787 Out-of-bounds Write. In the context of the MITRE ATT&CK framework, successful exploitation maps to T1203 Exploitation for Client Execution, where malicious code is executed on a victim's system via a trusted application like a web browser. The impact extends beyond mere confidentiality and integrity breaches; it poses a significant threat to availability as well, since memory corruption can cause the browser process or even the entire operating system instance to crash due to segmentation faults or access violations triggered by invalid memory references.
The vulnerability has been addressed in Firefox version 158, as well as in the Extended Support Release branches versions 115.43 and 153.5. These updates implement rigorous input validation and size checks within the graphics rendering pipeline to ensure that calculated buffer sizes do not exceed available memory limits or cause integer wraparound conditions. For organizations relying on these browser variants, it is imperative to verify that all endpoints are updated to at least one of the specified patched versions immediately. Automated patch management systems should be configured to prioritize this update due to its high severity and active exploitation potential in the wild. Additionally, deploying content security policies and restricting script execution from untrusted origins can provide an additional layer of defense by limiting the attack surface available to adversaries attempting to trigger these rendering flaws through malicious web pages.