Is CVE-2020-9309 actively exploited?

No active exploitation of CVE-2020-9309 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2020-9309 be exploited remotely?

Yes. CVE-2020-9309 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2020-9309?

CVE-2020-9309 has a CVSS score of 8.8 (HIGH).

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HIGH

CVE-2020-9309

CWE-434Published: July 15, 2020· Updated: Jun 17, 2026

8.8

CVSS v3.1

Official Description

Silverstripe CMS through 4.5 can be susceptible to script execution from malicious upload contents under allowed file extensions (for example HTML code in a TXT file). When these files are stored as protected or draft files, the MIME detection can cause browsers to execute the file contents. Uploads stored as protected or draft files are allowed by default for authorised users only, but can also be enabled through custom logic as well as modules such as silverstripe/userforms. Sites using the previously optional silverstripe/mimevalidator module can configure MIME whitelists rather than extension whitelists, and hence prevent this issue. Sites on the Common Web Platform (CWP) use this module by default, and are not affected.

NVD Source

Technical Analysis

CVE-2020-9309 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 8.8.