Origin Validation Error in elysia-cors Library by ElysiaJS

CVE-2025-50864

What is CVE-2025-50864?

CVE-2025-50864 is a vulnerability found in the elysia-cors library developed by ElysiaJS, which is used for managing Cross-Origin Resource Sharing (CORS) in web applications. CORS is a security feature that regulates how resources on a web server can be requested from a different domain. The vulnerability stems from an origin validation error, where the library incorrectly assesses the validity of submitted origins by checking for substring matches against a whitelist instead of requiring exact matches. This flaw creates substantial risk, as attackers can exploit it to gain unauthorized access to sensitive user data on affected sites. For example, malefactors could use a domain such as "example.common.net" or "notexample.com" to successfully bypass restrictions if "example.com" is included in the CORS policy.

Potential impact of CVE-2025-50864

1. Unauthorized Data Access: The primary risk is that attackers can retrieve sensitive information from web applications that utilize the elysia-cors library, as they can send requests from unauthorized origins.

2. Data Leakage: Organizations may experience severe data breaches if attackers manage to exploit this vulnerability, exposing user data such as personal information, payment details, and other sensitive content.

3. Malicious Exploitation: The presence of this vulnerability significantly raises the chances of further attacks, including the potential incidence of malware deployment or phishing campaigns aimed at users whose data has been compromised.

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