CVE-2026-87523 in Chrome
Summary
by MITRE • 09/09/2026
Race condition in DataTransfer in Google Chrome prior to 153.0.8010.36 allowed a remote attacker leveraging social engineering to obtain sensitive information via a crafted HTML page. (Chromium security severity: Low)
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified as a race condition within the DataTransfer interface of Google Chrome prior to version 153.0.8010.36 represents a subtle but significant flaw in how browser state is managed during asynchronous operations involving clipboard data and drag-and-drop events. This issue stems from a timing discrepancy where multiple threads or event handlers access shared resources without proper synchronization mechanisms, allowing an attacker to manipulate the sequence of execution. By crafting a specific HTML page that triggers these race conditions through carefully timed JavaScript interactions, an adversary can exploit the window between state initialization and finalization to intercept or alter data intended for other processes or users. The severity is classified as low by Chromium security standards because successful exploitation requires user interaction, specifically social engineering tactics such as convincing a victim to visit a malicious site or interact with specific elements on that page.
From a technical perspective, the DataTransfer object serves as an interface for handling drag-and-drop operations and clipboard events in web applications. It holds data about what is being dragged or copied, including MIME types and actual content. In this vulnerability scenario, the race condition likely occurs when concurrent access to the DataTransfer instance leads to inconsistent state retrieval. An attacker can craft a webpage that initiates multiple rapid-fire drag-and-drop or copy-paste events, attempting to read sensitive information from the clipboard or internal browser storage before it is properly sanitized or cleared by subsequent operations. This allows for the exfiltration of data such as passwords, personal identification numbers, or other confidential text content stored in the user's clipboard buffer. The exploit relies on precise timing and often requires the victim to have previously copied sensitive information, making the attack context-dependent but potentially devastating if successful.
The operational impact of this vulnerability centers on confidentiality breaches rather than integrity or availability issues. A remote attacker leveraging social engineering can trick a user into loading a malicious webpage that executes scripts designed to probe for clipboard contents via the DataTransfer API. If the race condition is successfully triggered, the script may capture sensitive text data before it is overwritten by normal browser behavior or cleared from memory. This poses a direct risk to users who rely on browsers as part of their workflow for copying and pasting credentials or private information. While the attack vector requires user engagement, which mitigates fully automated remote code execution risks, it remains dangerous in environments where high-value data is frequently copied and pasted across applications. The low severity rating reflects the difficulty of reliable exploitation due to browser-specific timing variations and modern security features like sandboxing that may limit the scope of damage even if the race condition is triggered.
Mitigation strategies primarily involve updating Google Chrome to version 153.0.8010.36 or later, where this synchronization issue has been resolved by implementing proper locking mechanisms or atomic operations within the DataTransfer handling code. Users and organizations should ensure that browser auto-update features are enabled to receive these patches promptly. Additionally, security awareness training is critical in mitigating social engineering aspects of such attacks; users must be educated about the risks of visiting untrusted websites while having sensitive data on their clipboard. From a defensive coding standpoint, web developers should avoid relying solely on client-side checks for sensitive operations and consider implementing additional verification layers or using more secure APIs that do not expose raw clipboard contents to arbitrary scripts without explicit user consent mechanisms enforced by the browser engine itself.
This vulnerability aligns with CWE-362, which describes concurrent execution race conditions where software performs multiple actions simultaneously but incorrectly handles these parallel executions leading to unintended behavior. In terms of threat modeling and adversary tactics, this exploit maps to ATT&CK technique T1059, specifically command scripting or web browser exploitation vectors that leverage legitimate system features for malicious purposes. The social engineering component also relates to ATT&CK tactic TA0001, Initial Access, where attackers use human interaction rather than pure technical exploits to gain footholds or extract data. Understanding these mappings helps security teams prioritize patching and monitoring efforts against similar race conditions in other web APIs that handle user input or system state asynchronously.