CVE-2026-78893 in Chrome
Summary
by MITRE • 08/26/2026
Information leak in QUIC in Google Chrome prior to 152.0.7977.65 allowed a remote attacker to leak sensitive information via a crafted HTML page. (Chromium security severity: Medium)
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as an information leak within the QUIC protocol implementation of Google Chrome versions prior to 152.0.7977.65 represents a significant breach in data confidentiality for users relying on this browser for secure web interactions. The Quick UDP Internet Connections, or QUIC, is a transport layer network protocol designed by Google and now standardized as IETF RFC 9000, intended to improve upon TCP by reducing latency and improving performance over unreliable networks. While the primary goal of QUIC includes encryption through TLS integration, flaws in its implementation can inadvertently expose sensitive data that should remain obscured from unauthorized parties. In this specific instance, a remote attacker could exploit the vulnerability by crafting a malicious HTML page that triggers an incorrect handling of network state or memory buffers within the browser's QUIC stack. This flaw allows for the exfiltration of internal application states, potentially including session tokens, authentication cookies, or other sensitive context information associated with active connections.
From a technical perspective, this issue falls under the category of improper restriction of operations within the bounds of a memory buffer or state machine, often categorized in industry standards as CWE-200: Information Exposure. The root cause likely stems from insufficient validation or sanitization of inputs processed by the QUIC engine when interacting with web content hosted on untrusted domains. When a user visits the crafted HTML page, the browser's rendering and networking layers process requests that interact with the QUIC implementation in an unexpected manner. This interaction leads to a state where internal variables are exposed through side channels or direct memory reads accessible via JavaScript APIs or DOM properties that were not intended for public access. The severity is rated as Medium by Chromium security teams, indicating that while exploitation requires user interaction such as visiting a specific webpage, the potential impact on privacy and session integrity is substantial enough to warrant immediate attention.
The operational impact of this vulnerability extends beyond simple data leakage; it compromises the fundamental trust model of web browsing where users expect their interactions with legitimate sites to remain private from third parties. An attacker leveraging this flaw could potentially hijack user sessions, perform unauthorized actions on behalf of the victim, or gather intelligence for further targeted attacks such as phishing or social engineering campaigns that rely on accurate contextual data about the victim's activities. Furthermore, because QUIC is increasingly adopted by major web services to enhance performance, vulnerabilities in its implementation affect a broad spectrum of modern web applications. The ability to leak information via a crafted HTML page means that no special plugins or elevated privileges are required for exploitation, making it accessible to any attacker who can lure victims to their malicious content through standard distribution vectors like email links, compromised websites, or drive-by downloads.
To mitigate the risks associated with this vulnerability, users must ensure they update Google Chrome to version 152.0.7977.65 or later as soon as possible. This patch includes corrections that address the underlying logic errors in the QUIC implementation, ensuring that sensitive internal states are properly isolated and not exposed to web content. Additionally, organizations should enforce strict Content Security Policies (CSP) across their domains to limit the ability of external scripts to access browser internals or perform cross-origin requests that might trigger such flaws. Monitoring for unusual network traffic patterns indicative of QUIC-based data exfiltration can also aid in detecting potential exploitation attempts in real-time. From a broader security posture perspective, this incident underscores the importance of regular vulnerability assessments and patch management cycles, particularly for components like transport protocols that are deeply integrated into modern browsers and frequently updated to address emerging threats aligned with ATT&CK techniques related to Collection via Browser or Network Sniffing depending on the specific vector utilized by attackers.