CVE-2026-121061 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Modularization 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)
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a use-after-free error within the Modularization component of Google Chrome prior to version 157.0.8103.38 represents a critical memory management flaw that compromises the integrity and confidentiality of user data. This specific defect arises when an object is deallocated from memory but remains accessible through dangling pointers, allowing subsequent operations to interact with freed or potentially reallocated memory regions. In the context of web browsers, such errors are particularly dangerous because they can be triggered by maliciously crafted HTML pages served over standard HTTP or HTTPS protocols. The attacker leverages this flaw to bypass Chrome's robust sandboxing mechanisms, which are designed to isolate untrusted content from sensitive system resources and user data. By exploiting the race condition inherent in use-after-free scenarios, a remote adversary can achieve arbitrary code execution within the browser process, effectively neutralizing the security boundaries that protect the underlying operating system.
From a technical perspective, this vulnerability is classified under CWE-416, which denotes Use After Free errors. The exploitation vector involves constructing an HTML page that triggers specific JavaScript or DOM manipulation sequences to cause the premature release of memory associated with modularization logic while retaining references to that same memory block. When the browser attempts to access these stale pointers during normal rendering or script execution, it may read from or write to arbitrary locations in memory. This capability allows for precise control over program flow and data states, facilitating techniques such as heap spraying or ROP chain construction depending on the specific environment and compiler protections present. The severity is rated high by Chromium security standards due to the ease of remote exploitation via a simple webpage visit, requiring no user interaction beyond loading the malicious content if other mitigations like click-to-play are disabled or bypassed.
The operational impact of this vulnerability extends far beyond potential data theft. Successful exploitation grants an attacker full control over the browser process, which can serve as a foothold for further lateral movement within a network environment. If the user is running with elevated privileges or if additional vulnerabilities exist in plugins or extensions loaded by Chrome, the scope of compromise expands significantly to include system-level access. This aligns closely with MITRE ATT&CK technique T1059, Command and Scripting Interpreter, as well as T1203, Exploitation for Client Execution. The ability to execute arbitrary code inside the sandbox is a significant breach because it undermines one of the primary defense-in-depth strategies employed by modern browsers. It allows attackers to install malware, exfiltrate sensitive information such as cookies and session tokens, or establish persistent backdoors without triggering typical security alerts associated with direct system-level exploits.
Mitigation for this vulnerability primarily involves immediate software updates. Users must upgrade Google Chrome to version 157.0.8103.38 or later, where the memory management logic in Modularization has been corrected to ensure proper reference counting and nullification of pointers after deallocation. Organizations should enforce automated update policies across all endpoints running this browser to minimize exposure windows. Additionally, security teams can implement network-level controls such as web filtering proxies that block access to known malicious domains or sandbox untrusted content before it reaches the endpoint. While user education regarding suspicious links remains relevant, technical mitigations are paramount given the remote and automatic nature of this exploit vector. Regular vulnerability scanning and patch management cycles are essential to maintain a secure posture against evolving browser-based threats.