Vulnerability in Open-Zaak
CVE-2020-26251
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.7 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.005 (37.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.000
Affected products
- Open-Zaak — versions < 1.3.3
- Openzaak Open Zaak
Weakness classification (CWE)
References
- github.com/open-zaak/open-zaak/security/advisories/GHSA-chhr-gxrg-64x7 (Third Party Advisory)
- github.com/open-zaak/open-zaak/commit/952269269f1b629fce9c94485f83ac13f31d6c46 (Patch, Third Party Advisory)
- github.com/open-zaak/open-zaak/blob/master/CHANGELOG.rst (Third Party Advisory, Release Notes)
Frequently asked questions
- What is CVE-2020-26251?
- CVE-2020-26251 is a medium-severity vulnerability in Open-Zaak, classified under Origin Validation Error. CVSS score: 4.7/10. Published 2020-12-18.
- How severe is CVE-2020-26251?
- Medium severity. CVSS v3 base score is 4.7 out of 10.