CVE-2026-121202 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Autofill in Google Chrome prior to 157.0.8103.38 allowed a remote attacker leveraging social engineering to potentially execute arbitrary code outside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a use-after-free condition within Google Chrome's Autofill component represents a critical memory management error that can be exploited by remote attackers through sophisticated social engineering tactics. This flaw resides in the handling of autofill data structures, which are responsible for managing user input suggestions and saved form information to enhance browsing convenience. When an attacker crafts a malicious HTML page designed to trigger specific interactions with these autofill mechanisms, they can induce a state where memory previously allocated for autofill objects is freed while references to that memory remain active within the application's runtime environment. This discrepancy creates a window of opportunity where the browser continues to operate on stale pointers, leading to undefined behavior and potential control over program execution flow.
From a technical perspective, use-after-free vulnerabilities are particularly dangerous because they allow an attacker to manipulate heap memory structures after their intended lifecycle has ended. In this specific instance within Chromium prior to version 157.0.8103.38, the flaw likely involves improper cleanup or reference counting logic when autofill data is processed or discarded. By carefully crafting a webpage that forces the browser to free certain autofill-related memory blocks while maintaining references through event handlers or DOM manipulation, an attacker can overwrite freed heap chunks with controlled data. This technique enables the injection of arbitrary code payloads into the process space, effectively bypassing standard security boundaries if the exploit chain is successfully completed.
The operational impact of this vulnerability is severe due to its potential for remote code execution outside the browser's sandbox environment. Google Chrome employs a multi-process architecture where renderer processes are isolated in sandboxes to limit the damage caused by exploits. However, use-after-free bugs can often be chained with other vulnerabilities or leveraged through specific rendering engine features to escape this confinement. If an attacker successfully executes arbitrary code outside the sandbox, they gain full control over the user's system, allowing for data theft, installation of malware, lateral movement within a network, and complete compromise of the host machine. The requirement for social engineering indicates that direct automated exploitation is less likely; instead, victims must be tricked into visiting the malicious page or interacting with crafted elements, which raises the bar for casual attackers but does not mitigate the severity for targeted campaigns.
This vulnerability aligns closely with Common Weakness Enumeration (CWE) category CWE-416, which defines use-after-free errors as a result of improper memory management practices that lead to accessing freed memory regions. Furthermore, in the context of the MITRE ATT&CK framework, this exploit path relates to techniques involving client-side code execution and potentially sandbox escape mechanisms such as T1059 or related privilege escalation vectors depending on how the out-of-bounds access is leveraged to break isolation boundaries. The Chromium security team has classified this issue with a medium severity rating, reflecting its potential for exploitation but also acknowledging the complexity required to reliably achieve arbitrary code execution in modern browser environments that include additional mitigations like heap hardening and ASLR.
To mitigate the risks associated with this vulnerability, organizations and individual users must ensure that Google Chrome is updated to version 157.0.8103.38 or later immediately upon availability. Since the attack vector involves social engineering via crafted HTML pages, user awareness training remains a vital secondary defense layer. Users should be educated to recognize suspicious links and avoid interacting with untrusted web content that attempts to manipulate form fields or trigger unexpected browser behaviors. Additionally, deploying endpoint detection and response solutions can help identify anomalous process behavior indicative of sandbox escape attempts, providing an additional layer of security against successful exploitation of this memory corruption flaw.