CVE-2026-121118 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in SVG in Google Chrome prior to 157.0.8103.38 allowed a remote attacker to execute arbitrary code inside 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 described constitutes a critical memory safety flaw within the SVG rendering engine of Google Chrome, specifically affecting versions prior to 157.0.8103.38. This issue is classified as an out-of-bounds use or use-after-free condition, which represents one of the most dangerous categories of software defects in modern web browsers. The root cause lies in improper memory management within the component responsible for parsing and rendering Scalable Vector Graphics. When a maliciously crafted HTML page containing specific SVG elements is processed by the browser, it triggers a sequence where previously allocated memory objects are freed or deallocated while still being referenced by other parts of the application logic. This discrepancy creates a dangling pointer situation where the software attempts to access memory that has already been returned to the system allocator for reuse.
From a technical perspective, this flaw exploits the complex interaction between JavaScript execution and native C++ rendering code in Chromium-based browsers. The SVG parser likely fails to properly invalidate references or update pointers when an object is destroyed during dynamic content manipulation. Consequently, subsequent operations targeting these invalidated objects result in undefined behavior. In many cases involving use-after-free vulnerabilities, attackers can manipulate the memory allocator to place controlled data structures at the address of the freed memory. By carefully crafting the payload within the HTML page, a remote attacker can achieve arbitrary read and write capabilities within the browser process context. This capability is particularly severe because it allows for precise control over program execution flow, leading directly to code execution.
The operational impact of this vulnerability is significant due to its potential for remote code execution via a crafted web page. Since modern browsers operate with sandboxing mechanisms designed to isolate untrusted content from the host operating system, gaining arbitrary code execution inside the browser process is often considered equivalent to breaking out of that sandbox if further exploitation techniques are applied. An attacker could leverage this flaw to execute malicious binaries, install persistent malware, or exfiltrate sensitive user data such as cookies, session tokens, and browsing history. The severity rating of High by Chromium security reflects the high likelihood of successful exploitation given the prevalence of SVG usage in web content and the relative ease with which memory corruption bugs can be stabilized for exploit development using modern heap grooming techniques.
This vulnerability maps directly to Common Weakness Enumeration identifier CWE-416, which describes Use After Free conditions where a pointer is used after it has been freed, leading to unpredictable behavior or security breaches. Furthermore, in the context of the MITRE ATT&CK framework, this flaw facilitates initial access and privilege escalation tactics. Attackers would typically distribute the crafted HTML page through phishing emails, compromised websites, or drive-by download scenarios. Once executed within the browser sandbox, the exploit could attempt to escape the containerized environment using additional kernel or renderer vulnerabilities, thereby achieving full system compromise on the victim's machine. The existence of such a flaw underscores the critical importance of memory-safe programming practices and rigorous fuzzing during software development cycles.
Mitigation strategies primarily involve immediate patching by upgrading Google Chrome to version 157.0.8103.38 or later, where these memory management issues have been resolved through code reviews and automated testing. For organizations unable to update immediately due to compatibility constraints, deploying browser isolation solutions such as Microsoft Edge IE Mode with sandboxed profiles or third-party virtualization appliances can mitigate the risk by preventing direct execution of untrusted web content on local systems. Additionally, enabling strict Content Security Policy headers and disabling JavaScript in low-trust environments can reduce the attack surface available for triggering these memory corruption bugs. Continuous monitoring for anomalous network activity originating from browser processes may also help detect exploitation attempts that bypass initial defenses.