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The default behavior is extremely dangerous.

High
fengmk2 published GHSA-qxrj-hx23-xp82 Dec 11, 2023

Package

npm @koa/cors (npm)

Affected versions

4.0.0

Patched versions

None

Description

Currently, the middleware operates in a way that if an allowed origin is not provided, it will return an Access-Control-Allow-Origin header with the value of the origin from the request. This behavior completely disables one of the most crucial elements of browsers - the Same Origin Policy (SOP), this could cause a very serious security threat to the users of this middleware.

If such behavior is expected, for instance, when middleware is used exclusively for prototypes and not for production applications, it should be heavily emphasized in the documentation along with an indication of the risks associated with such behavior, as many users may not be aware of it.

Severity

High

CVE ID

CVE-2023-49803

Weaknesses

No CWEs

Credits