CVE-2026-87456 in Chrome
Summary
by MITRE • 09/09/2026
Uninitialized resource in Media in Google Chrome prior to 153.0.8010.36 allowed a remote attacker who had compromised the renderer process to read memory outside the sandbox via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as an uninitialized resource issue within Google Chrome prior to version 153.0.8010.36 represents a critical failure in memory management practices during media processing operations. This flaw specifically affects the browser's handling of multimedia content, where specific data structures or buffers are allocated but not properly initialized before being accessed by subsequent code paths. In secure software development, uninitialized variables can contain residual data from previous allocations, leading to unpredictable behavior when that memory is read. The severity of this issue is classified as Medium within the Chromium security framework, indicating a significant risk that requires prompt attention despite not being immediately critical for all user scenarios.
The operational impact of this vulnerability is particularly severe due to its exploitation vector and scope. A remote attacker who has already compromised the renderer process can leverage this flaw to read memory outside the sandbox boundary. This scenario typically arises when an attacker exploits a separate, lower-severity vulnerability within the same renderer process to gain initial foothold control. Once inside the renderer, which is designed with strict isolation from sensitive system resources and user data through sandboxing mechanisms, the uninitialized resource bug allows for out-of-bounds memory reads. By crafting a specific HTML page that triggers this media processing path under precise conditions, an attacker can cause the browser to leak contents of adjacent memory regions into accessible locations within the renderer process.
This capability effectively bypasses one of the primary defense-in-depth layers employed by modern web browsers: sandboxing. The sandbox restricts what code running in a tab or frame can do with system resources, preventing direct access to files, network interfaces, and other processes. When an attacker achieves out-of-bounds read capabilities within this confined environment, they gain visibility into memory segments that should remain inaccessible. This information leak can be used to gather sensitive data such as passwords stored in the browser's password manager, session cookies granting unauthorized access to web applications, or cryptographic keys essential for secure communications. The ability to exfiltrate arbitrary memory contents fundamentally undermines the integrity and confidentiality guarantees provided by the sandbox architecture.
From a classification perspective, this vulnerability aligns with CWE-457, which describes the use of an uninitialized variable. This category encompasses scenarios where software uses variables that have not been assigned a value prior to their first usage, leading to undefined behavior or information disclosure. Furthermore, in terms of offensive security tactics, this exploitation technique corresponds to ATT&CK T1005, specifically Data from Local System, as it involves the collection and exfiltration of data directly from the victim's machine through memory scraping techniques facilitated by browser vulnerabilities. The progression from renderer compromise to sandbox escape via information leakage is a common pattern in advanced persistent threats targeting high-value targets using web-based entry points.
Mitigation strategies for this vulnerability primarily involve immediate software updates. Users must upgrade Google Chrome to version 153.0.8010.36 or later, where the initialization logic has been corrected to ensure all resources are properly zeroed out or assigned default values before use in media processing pipelines. For organizations managing large fleets of devices, automated patch management systems should be configured to prioritize this update due to its potential for sandbox escape via chained exploits. Additionally, deploying browser hardening policies such as disabling JavaScript execution on untrusted sites can reduce the attack surface by preventing the rendering and execution of crafted HTML pages that trigger these media processing paths. Security teams should also monitor for indicators of compromise related to renderer process anomalies or unusual memory access patterns within endpoint detection and response systems to identify potential exploitation attempts in real-time.