CVE-2020-26251 CORS configuration is possibly vulnerable
Open Zaak had overly permissive CORS settings allowing cross-origin requests, though mitigated by other security controls, requiring an upgrade to secure defaults.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2020-26251?
CVE-2020-26251 is a medium-severity vulnerability in open-zaak, published on 18 Dec 2020. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Open Zaak is a modern, open-source data- and services-layer to enable zaakgericht werken, a Dutch approach to case management. In Open Zaak before version 1.3.3 the Cross-Origin-Resource-Sharing policy in Open Zaak is currently wide open - every client is allowed. This allows evil.com to run scripts that perform AJAX calls to known Open Zaak installations, and the browser will not block these. This was intended to only apply to development machines running on localhost/127.0.0.1. Open Zaak 1.3.3 disables CORS by default, while it can be opted-in through environment variables. The vulnerability does not actually seem exploitable because: a) The session cookie has a `Same-Site: Lax` policy which prevents it from being sent along in Cross-Origin requests. b) All pages that give access to (production) data are login-protected c) `Access-Control-Allow-Credentials` is set to `false` d) CSRF checks probably block the remote origin, since they're not explicitly added to the trusted allowlist.
Weakness: CWE-346
Which versions are affected by CVE-2020-26251?
It affects 1 product.
Products include Openzaak Open Zaak.
How do I fix CVE-2020-26251?
No fix has been published for CVE-2020-26251 yet. Limit exposure of the affected software until one is available.
Is CVE-2020-26251 being exploited?
There is no known exploitation of CVE-2020-26251 in the wild and no public exploit code.
Sources
Also known as GHSA-chhr-gxrg-64x7.