Description

Activepieces is an open source AI workflow automation platform. Prior to 0.83.0, the /api/redirect OAuth callback endpoint embeds the user-supplied code query parameter directly into an inline script block without proper escaping. A crafted request to /api/redirect with a malicious code value can break out of the script context and execute arbitrary JavaScript in the Activepieces origin when a logged-in user opens it. An unauthenticated attacker can access the victim's session tokens or make authenticated API calls on the victim's behalf. This issue is fixed in version 0.83.0.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.1",
  "pubDate": "2026-08-11T17:19:16.420Z",
  "pubdate": "2026-08-11T17:19:16.420Z",
  "executiveSummary": "An unauthenticated Reflected Cross-Site Scripting (XSS) vulnerability exists within the Activepieces AI workflow automation platform prior to version 0.83.0. The security flaw resides in the OAuth callback endpoint at /api/redirect, where user-supplied input provided via the code query parameter is dynamically embedded directly into an inline JavaScript block without proper sanitization, escaping, or context-aware encoding.\nIf a victimized user who is actively authenticated within the Activepieces application is induced to interact with a crafted malicious URL, the injected payload breaks out of the intended script execution context. This results in the execution of arbitrary JavaScript code executing within the victim's browser under the origin and security context of the Activepieces application.\nSuccessful exploitation allows an external, unauthenticated attacker to compromise user sessions, access sensitive session tokens, and issue unauthorized authenticated API calls on behalf of the victim. This elevates the risk profile significantly, potentially leading to unauthorized workflow modifications or further compromise of the automation platform.\nMitigation requires upgrading the Activepieces deployment to version 0.83.0 or later, where proper output encoding and context-aware sanitization mechanisms are enforced on the vulnerable /api/redirect endpoint.",
  "technicalDetails": "The vulnerability is classified as a Reflected Cross-Site Scripting (XSS) flaw localized within the OAuth redirect mechanism of the Activepieces application. The vulnerable component is the server-side endpoint exposed at the URL path /api/redirect.\nThe root cause of the vulnerability stems from improper input validation and the lack of output encoding. Specifically, the application extracts the user-supplied input parameter named code from incoming HTTP GET requests associated with the OAuth callback flow. This input is then dynamically concatenated and embedded directly into an inline HTML script block rendered in the HTTP response body without prior context-aware escaping.\nAttackers can leverage this implementation flaw by crafting a specialized HTTP request targeting the /api/redirect endpoint, supplying a malicious JavaScript payload structured to break out of the native script context (e.g., terminating existing script tags or string literals).\nThe attack flow proceeds as follows: First, an unauthenticated attacker constructs a malicious URL pointing to the vulnerable /api/redirect endpoint with an injected payload within the code parameter. Second, the attacker induces an authenticated Activepieces user to click or otherwise load this crafted URL, typically via social engineering or phishing vectors. Third, the user's browser issues the request to the Activepieces server over the network. Fourth, the server processes the request, embeds the malicious code parameter unsanitized into the inline script block, and returns the HTTP response to the browser. Fifth, the victim's browser parses the response, interprets the injected script, and executes the arbitrary JavaScript payload within the Activepieces origin.\nBecause the execution occurs in the context of an authenticated session, the malicious payload possesses full access to Document Object Model (DOM) elements, cookies, and local storage associated with the Activepieces origin. Consequently, post-exploitation impact includes the exfiltration of sensitive session tokens, unauthorized access to user account data, and the execution of authenticated API requests performing administrative or workflow automation tasks on behalf of the victim.\nThe affected product is Activepieces, specifically versions prior to 0.83.0. Exploitation requires network exposure of the API endpoint, does not require prior authentication or privileges for the attacker, but does require user interaction via a logged-in victim."
}