CVE-2026-121084 in Chrome
Summary
by MITRE • 11/03/2026
Out of bounds read in Skia in Google Chrome prior to 157.0.8103.38 allowed a remote attacker who had compromised the renderer process to execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 11/04/2026
The vulnerability identified as an out-of-bounds read within the Skia graphics library, present in versions of Google Chrome prior to 157.0.8103.38, represents a critical failure in memory safety protocols during the rendering of web content. This flaw is rooted in improper boundary checks when processing specific graphical operations or image data structures handled by Skia. When a remote attacker crafts an HTML page containing maliciously constructed graphics commands or malformed media assets, they can trigger this out-of-bounds read condition within the renderer process. The primary technical consequence of such a memory access violation is typically information disclosure, where sensitive data from adjacent memory regions may be leaked to the application. However, in complex environments like browser renderers that utilize sophisticated JIT compilers and dynamic code generation for performance optimization, an initial arbitrary read can often serve as a primitive for more severe exploitation chains. By carefully controlling the content of the read operation, an attacker might achieve information leaks sufficient to bypass address space layout randomization or other memory protection mechanisms, thereby facilitating further steps toward remote code execution.
The operational impact is significantly amplified by the context in which this vulnerability occurs: within the renderer process sandbox. Modern browsers employ a multi-process architecture where each tab runs in a restricted environment known as a sandbox, designed to limit the damage if an attacker successfully exploits a vulnerability. The Chromium security severity rating of High reflects the potential for privilege escalation from this confined state. Although the initial flaw is classified as an out-of-bounds read rather than a write, which generally limits direct code execution capabilities, advanced exploitation techniques can leverage information leaks obtained through such reads to construct arbitrary memory writes or control flow hijacking primitives. This allows a compromised renderer process to escape its sandbox boundaries and execute arbitrary code with higher privileges on the host system. The attacker does not need physical access or user interaction beyond visiting a malicious webpage, making this a viable vector for drive-by attacks targeting users who browse untrusted content.
From a classification perspective, this vulnerability aligns closely with CWE-125, which defines out-of-bounds read errors resulting from incorrect index calculations or missing boundary checks on array accesses. In the context of browser exploitation and sandbox escape techniques, it also relates to ATT&CK technique T1059, Command and Scripting Interpreter, as part of a broader chain leading to execution outside the controlled environment. The reliance on Skia, a widely used 2D graphics library across multiple platforms including Android and Chrome OS, means that this flaw potentially affects a broad ecosystem beyond just desktop browsers. Developers must ensure that all graphical operations validate input dimensions against allocated buffer sizes before processing pixel data or applying transformations. Mitigation strategies primarily involve the immediate application of vendor-provided patches to update the browser version to 157.0.8103.38 or later, which includes corrected boundary checks within the Skia integration layer. Additionally, organizations should enforce strict content security policies and utilize sandboxing technologies that further restrict renderer process capabilities, reducing the likelihood that an initial memory safety violation can be successfully chained into a full system compromise.