CVE-2023-49803
Prior to version 5.0.0, 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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.28%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
@koa/cors npm provides Cross-Origin Resource Sharing (CORS) for koa, a web framework for Node.js. Prior to version 5.0.0, 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. Version 5.0.0 fixes this vulnerability.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 0.28% probability · 20th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-346
- Affected
- koajs/cross-origin resource sharing for koa
- Source
- security-advisories@github.com
References
- https://github.com/koajs/cors/commit/f31dac99f5355c41e7d4dd3c4a80c5f154941a11Patch
- https://github.com/koajs/cors/security/advisories/GHSA-qxrj-hx23-xp82Vendor Advisory
- https://github.com/koajs/cors/commit/f31dac99f5355c41e7d4dd3c4a80c5f154941a11Patch
- https://github.com/koajs/cors/security/advisories/GHSA-qxrj-hx23-xp82Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.