CVE-2020-26251 Information

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.

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N

Reference

https://github.com/open-zaak/open-zaak/commit/952269269f1b629fce9c94485f83ac13f31d6c46 https://github.com/open-zaak/open-zaak/security/advisories/GHSA-chhr-gxrg-64x7 https://github.com/open-zaak/open-zaak/blob/master/CHANGELOG.rst#133-2020-12-17

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction Required

NONE

Scope

REQUIRED

Confidentiality Impact

CHANGED

Integrity Impact

LOW

Availability Impact

LOW

Base Score

NONE

Base Severity

4.7