CVE-2026-91720 in Chrome
Summary
by MITRE • 09/16/2026
Uninitialized resource in ANGLE in Google Chrome prior to 153.0.8010.47 allowed a remote attacker to read memory outside the sandbox via a crafted HTML page. (Chromium security severity: High)
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Analysis
by VulDB Data Team • 09/16/2026
The vulnerability identified as an uninitialized resource issue within the ANGLE graphics library, present in versions of Google Chrome prior to 153.0.8010.47, represents a critical failure in memory management and state initialization. ANGLE serves as the translation layer between web applications and native GPU APIs such as OpenGL ES or Vulkan, enabling browsers like Chrome to render complex graphics efficiently. When this component fails to properly initialize specific resources before they are accessed, it leaves undefined data in memory locations that subsequent operations may read. This lack of proper initialization creates a scenario where the application does not guarantee that the memory contains valid, expected values derived from secure sources, but rather retains whatever residual data was previously stored at those addresses.
From a technical perspective, this flaw is classified under CWE-457, which describes the use of an uninitialized variable or resource. In the context of browser security, such vulnerabilities are particularly dangerous because they can lead to out-of-bounds reads when the uninitialized memory contains pointers or size values that exceed expected bounds. An attacker who crafts a malicious HTML page containing specific JavaScript code and WebGL commands can trigger this condition during the rendering process. By carefully constructing the input data sent to the ANGLE layer, the attacker forces the browser to access memory regions that are not part of the intended allocation for that graphics operation. This results in the leakage of sensitive information stored in adjacent memory blocks, effectively bypassing the sandbox isolation mechanisms designed to contain web content and prevent it from accessing privileged system resources or other tabs' data.
The operational impact of this vulnerability is severe due to its potential for remote code execution or significant privacy breaches through side-channel attacks. Although the primary manifestation described involves reading memory outside the sandbox, such information disclosure can serve as a stepping stone for more complex exploits. An attacker could potentially use the leaked memory contents to defeat address space layout randomization (ASLR) by discovering base addresses of critical libraries and modules within the browser process. With this knowledge, further exploitation techniques become feasible, allowing the attacker to execute arbitrary code with the privileges of the compromised user account. The Chromium security severity rating of High reflects the realistic possibility that a skilled adversary could leverage this flaw in a remote attack scenario without requiring any interaction beyond visiting a malicious webpage hosted on a server controlled by the attacker.
To mitigate risks associated with this vulnerability, users must ensure their browsers are updated to version 153.0.8010.47 or later, where these initialization checks and memory safety improvements have been implemented. For organizations managing large fleets of devices, deploying automated patch management systems is essential to minimize the window of exposure. Additionally, security teams should monitor for indicators of compromise that might suggest exploitation attempts, such as unusual network traffic patterns originating from browser processes or unexpected behavior in graphics-related subsystems. While user education remains important, technical controls like endpoint detection and response solutions configured to detect anomalous memory access patterns can provide an additional layer of defense against sophisticated attacks targeting this class of vulnerabilities.
This incident underscores the importance of rigorous code review practices for low-level components that interact directly with hardware resources. The integration of static analysis tools capable of detecting uninitialized variable usage, along with dynamic testing methods like fuzzing and address sanitizer instrumentation during development cycles, can help identify such flaws before they reach production builds. Furthermore, adher to industry standards such as the MITRE ATT&CK framework helps in understanding how this vulnerability fits into broader attack chains. Specifically, techniques related to initial access via spearphishing or drive-by downloads often rely on exploiting browser vulnerabilities like this one to establish a foothold within an organization's network infrastructure. By addressing these root causes through improved development practices and timely updates, organizations can significantly reduce their exposure to high-severity web-based attacks.