Bottom line: An unpatched zero-day in VS Code/github.dev enables theft of GitHub OAuth tokens via manipulated links, providing access to all private repositories of a victim.
A publicly disclosed exploit for an unpatched vulnerability in Visual Studio Code allows attackers to steal GitHub OAuth tokens by tricking developers into clicking manipulated links. Microsoft has not yet provided a patch for this zero-day.
Security researcher Ammar Askar has publicly disclosed code for a zero-day vulnerability in Visual Studio Code. The vulnerability affects github.dev, the browser-based version for editing GitHub repositories directly in a web browser. The attack vector exploits the isolated messaging system within the webview of Visual Studio Code.
An attacker can trick a victim into clicking a crafted link. The provided proof-of-concept exploit executes malicious JavaScript code within the webview, which simulates keyboard input to install a malicious extension in the background. This extension intercepts the GitHub OAuth token transmitted when the page loads and queries the GitHub API to list all private repositories the victim has access to. The token is not limited to a specific repository but provides full access to all repositories the user can access.
For CISOs, it is relevant that at the time of publication, no CVE identifier had been assigned and Microsoft has not provided an official patch. The risk affects all developers using github.dev or VS Code and authenticated via GitHub. The attack surface is large, as exploitation requires only a click on a crafted link.
As a temporary countermeasure, users can delete cookies and local site data stored in the browser for the github.dev domain. This can be done via the lock icon or the settings icon in the address bar. By clearing this local data, an explicit security warning is forced to appear when attempting to reconnect via a manipulated link, displaying a dialog requesting login and interrupting the automated token theft.
Askar justified the immediate disclosure without observing standard embargo periods by citing negative experiences with the Microsoft Security Response Center (MSRC). He gave GitHub’s security team only one hour advance notice. Microsoft has previously silently fixed security vulnerabilities in Visual Studio Code that he reported without crediting the discoverer or acknowledging the security risk.
Source: www.it-daily.net · Published June 5, 2026
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