CVE-2020-26251

Medium

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.

SeverityMedium
CVSS4.7
Exploit probability—
ProductOpenzaak Open Zaak
PublishedDec 18, 2020
First seenDec 18, 2020
Weakness typeCWE-346CWE-346

How to fix

Update
  • openzaak open_zaak1.3.3 or later

Affected products

ProductAffected versionsFixed in
openzaak open_zaakv < 1.3.31.3.3

Check your version

Choose the product and enter the version you run to see whether it falls in the affected range.

In the Intelligence 360 plan

Attack Surface Management

See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.