CVE-2026-121217 in Chrome
Summary
by MITRE • 11/03/2026
Use after free in Streaming in Google Chrome prior to 157.0.8103.38 allowed an adjacent attacker to execute arbitrary code inside the sandbox via crafted network traffic. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 11/03/2026
The vulnerability identified as a use-after-free error within the streaming components of Google Chrome prior to version 157.0.8103.38 represents a critical memory management flaw that undermines the browser's sandboxing mechanisms. This specific class of defect occurs when the application continues to reference a memory block after it has been freed, leading to undefined behavior that can be exploited by an attacker. In this context, the vulnerability is located within the network stack responsible for handling streaming data, which processes incoming traffic from various sources including web pages and extensions. The severity rating assigned by Chromium as Low reflects the complexity of exploitation or the limited attack surface in typical scenarios, but it does not diminish the potential impact if successfully leveraged against a targeted victim.
From a technical perspective, use-after-free vulnerabilities arise when pointers to deallocated memory are accessed without proper validation or reallocation checks. When an attacker crafts specific network traffic designed to trigger this condition, they can manipulate how the browser interprets the freed memory region. This manipulation allows for arbitrary code execution within the context of the Chrome process. Although modern browsers employ robust sandboxing techniques that restrict processes from accessing sensitive system resources directly, a successful exploit in this scenario indicates a breach of these isolation boundaries. The attacker gains the ability to execute instructions with the privileges of the compromised browser instance, which can serve as a foothold for further lateral movement or data exfiltration within the user's environment.
The operational impact of such a vulnerability is significant despite its low severity classification in internal tracking systems. An adjacent attacker, potentially one who controls network traffic directed at the victim or intercepts it via man-in-the-middle techniques depending on the specific streaming protocol involved, can achieve remote code execution without any user interaction beyond visiting a malicious site or receiving crafted data. This aligns with common attack vectors described in industry standards such as CWE-416, which defines use-after-free errors as a primary cause of software instability and security breaches. Furthermore, this exploitation path relates to ATT&CK techniques involving initial access through drive-by compromises and execution within the sandbox environment, highlighting the importance of maintaining up-to-date browser versions to mitigate these risks.
Mitigation strategies primarily involve updating Google Chrome to version 157.0.8103.38 or later, where the underlying memory management logic has been corrected to prevent access to freed resources. Organizations should ensure that automatic update mechanisms are enabled for all endpoints running this browser to minimize exposure windows. Additionally, security teams can implement network-level controls such as deep packet inspection or web application firewalls to detect and block anomalous streaming traffic patterns associated with exploitation attempts. While user education remains relevant, the technical fix provided by the vendor is the most effective defense against this specific memory corruption flaw. Regular patch management cycles are essential to address these types of vulnerabilities before they can be weaponized in widespread attacks.