Description

Sandbox escape due to use-after-free in the Graphics component. This vulnerability was fixed in Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.6",
  "pubDate": "2026-09-29T13:17:43.583Z",
  "pubdate": "2026-09-29T13:17:43.583Z",
  "executiveSummary": "A critical memory safety vulnerability exists in the Graphics component of Firefox, manifesting as a use-after-free (UAF) flaw. This vulnerability facilitates a sandbox escape, allowing an attacker to break out of the browser's restricted rendering process.\nThe vulnerability affects multiple versions of the Firefox ecosystem, specifically Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.\nBy successfully exploiting this flaw, a remote attacker can achieve arbitrary code execution outside the intended security boundaries of the browser sandbox. This compromises the integrity and confidentiality of the underlying host system.\nExploitation typically requires enticing a user to interact with malicious web content designed to trigger the vulnerable graphics operation. Given the nature of UAF vulnerabilities, this represents a high-risk security event that bypasses the primary sandbox defense mechanism, granting the attacker the effective privileges of the browser process or potentially the user context upon successful escape.",
  "technicalDetails": "The vulnerability is rooted in improper memory management within the Firefox Graphics component. A use-after-free (UAF) occurs when a program continues to hold a pointer to a memory location after that memory has been freed or deallocated. If the application later accesses this dangling pointer, it can lead to undefined behavior, memory corruption, or arbitrary code execution.\nIn the context of the Firefox Graphics component, the issue likely stems from a race condition or an incorrect object lifetime management cycle. Graphics operations often involve complex asynchronous interactions between the main process and the GPU-accelerated rendering process. If an object—such as a surface, texture, or rendering primitive—is freed while still referenced by a pending command or a cache entry, a UAF condition is established.\nThe exploitation flow typically begins with heap grooming, where the attacker injects malicious data to manipulate the memory layout. By forcing the browser to allocate and deallocate specific objects in a predictable pattern, the attacker aims to place a controlled payload at the memory address previously occupied by the freed graphics object. When the graphics engine subsequently attempts to dereference the dangling pointer, it inadvertently executes or utilizes the attacker-supplied data.\nThis vulnerability is particularly severe because it targets the sandbox architecture. The browser sandbox is designed to prevent malicious code from accessing the filesystem, OS APIs, or other sensitive areas of the machine. By achieving a UAF condition within the Graphics subsystem, an attacker can hijack the control flow of the rendering process. If the exploited component has sufficient permissions or interfaces with higher-privileged IPC (Inter-Process Communication) channels, the attacker can leverage the UAF to execute arbitrary instructions, thereby breaking the sandbox isolation.\nThis flaw affects Firefox ESR 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17. The attack is generally categorized as a remote exploit, as it can be triggered via specially crafted web content (e.g., HTML, CSS, or WebGL shaders) processed by the graphics component. Successful exploitation does not require prior authentication, though user interaction, such as visiting a compromised website, is a primary prerequisite. Post-exploitation impact includes full compromise of the user's browser session, potential access to local user data, and the capability for the attacker to maintain persistence or pivot into the underlying operating system environment."
}