@koa/cors has overly permissive origin policy
CVE-2023-49803
What is CVE-2023-49803?
@koa/cors, a middleware package for the Koa web framework, was found to have a significant security flaw where it improperly handles requests without specified allowed origins. In versions prior to 5.0.0, the middleware would return an 'Access-Control-Allow-Origin' header based on the request origin, undermining the Same Origin Policy (SOP). This can lead to severe security issues by allowing potentially malicious domains to access and manipulate the resources of an application. Users must be aware of this behavior and exercise caution, especially when using this middleware in production environments. It is recommended to upgrade to version 5.0.0 or later to mitigate this risk.

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Affected Version(s)
cors < 5.0.0
References
CVSS V3.1
Timeline
Vulnerability published
Vulnerability Reserved
