CVE-2020-26251

MEDIUMNVD 4.74.7—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.7 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 64% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
4.7
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.7Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
4.7
EG Score
4.7(medium)
EPSS
36.5%
KEV
Not listed

Published

December 18, 2020

Last Modified

November 21, 2024

References (6)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 44× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 22:37 UTCEG score recompute
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  68. 2026-05-23 04:00 UTCEG score recompute

Frequently asked(5)

What is CVE-2020-26251?
CVE-2020-26251 is a medium vulnerability published on December 18, 2020. 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…
When was CVE-2020-26251 disclosed?
CVE-2020-26251 was first published in the National Vulnerability Database on December 18, 2020, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-26251 actively exploited?
CVE-2020-26251 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 36.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2020-26251?
CVE-2020-26251 has a CVSS v3 base score of 4.7 (NVD).
How do I remediate CVE-2020-26251?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-26251, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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