CVE-2023-49803

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.

How to fix CVE-2023-49803

To remediate CVE-2023-49803, upgrade the affected package to a fixed version below.

• —upgrade to 5.0.0 or later

Is CVE-2023-49803 being exploited?

Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.

Affected packages (1)

• from 0, < 5.0.0

CVSS scores

References (4)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2023-49803
• PATCHgithub.com/koajs/cors
• WEBgithub.com/koajs/cors/commit/f31dac99f5355c41e7d4dd3c4a80c5f154941a11
• WEBgithub.com/koajs/cors/security/advisories/GHSA-qxrj-hx23-xp82