Overview
This article details a cross-site scripting (XSS) vulnerability identified as CVE-2025-66040 in Spotipy, a popular Python library for interacting with the Spotify Web API. This vulnerability affects applications using Spotipy for OAuth authentication. Specifically, the issue lies within the OAuth callback server, where user-supplied data is not properly sanitized, leading to potential JavaScript injection. Users are strongly advised to update to Spotipy version 2.25.2 or later to mitigate this risk.
Technical Details
The vulnerability stems from insufficient input validation of the error parameter in the OAuth callback URL. When an error occurs during the OAuth authorization flow, Spotipy’s internal server passes this error message back to the user’s browser. Prior to version 2.25.2, the error parameter wasn’t properly sanitized, allowing an attacker to inject arbitrary JavaScript code into the response. This malicious script could then execute in the context of the user’s browser, potentially leading to session hijacking, data theft, or other malicious activities.
CVSS Analysis
CVE-2025-66040 has been assigned a CVSS score of 3.6 (Low). While the score is relatively low, the potential impact should not be ignored. The CVSS vector string is likely AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N.
Here’s a breakdown:
- Attack Vector (AV): Network (N) – The vulnerability can be exploited over the network.
- Attack Complexity (AC): Low (L) – The vulnerability is relatively easy to exploit.
- Privileges Required (PR): None (N) – No privileges are required to exploit the vulnerability.
- User Interaction (UI): Required (R) – User interaction is required to trigger the vulnerability (e.g., clicking a malicious link).
- Scope (S): Unchanged (U) – An exploited vulnerability can only affect resources managed by the same security authority.
- Confidentiality Impact (C): None (N) – There is no impact to confidentiality.
- Integrity Impact (I): Low (L) – There is a low impact to integrity. An attacker might be able to modify some data, but the overall system integrity is not significantly affected.
- Availability Impact (A): None (N) – There is no impact to availability.
The low score is mainly due to the need for user interaction (clicking a malicious link during the OAuth flow) and the limited impact (potential for script execution but not necessarily system compromise).
Possible Impact
Although the CVSS score is low, successful exploitation of this XSS vulnerability can lead to:
- Session Hijacking: An attacker could potentially steal a user’s session cookie and gain unauthorized access to their Spotify account or the application integrating Spotipy.
- Data Theft: Malicious JavaScript code could be injected to steal sensitive data from the user’s browser, such as stored credentials or personal information.
- Redirection to Phishing Sites: The attacker could redirect the user to a fake login page to harvest their Spotify credentials.
- Defacement: The attacker could modify the appearance of the application within the user’s browser.
Mitigation and Patch Steps
The primary mitigation step is to upgrade to Spotipy version 2.25.2 or later. This version includes a patch that properly sanitizes the error parameter in the OAuth callback, preventing JavaScript injection.
You can upgrade Spotipy using pip:
pip install --upgrade spotipyAdditionally, consider implementing these general security best practices:
- Input Validation: Always validate and sanitize all user-supplied data before displaying it or using it in your application.
- Output Encoding: Properly encode output to prevent XSS attacks.
- Content Security Policy (CSP): Implement a strong CSP to restrict the sources from which the browser can load resources.
References
- CVE ID: CVE-2025-66040
- Spotipy Commit: https://github.com/spotipy-dev/spotipy/commit/880b92d7243dcf2b83bf31dc365a858d8b5e6767
- Spotipy Security Advisory: https://github.com/spotipy-dev/spotipy/security/advisories/GHSA-r77h-rpp9-w2xm
