Arbitrary file upload in Silverstripe Mimevalidator
CVE-2020-9309
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.
Vulnerability class: Unrestricted File Upload
EPSS: 0.018 (76.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.
Affected products
- Silverstripe Mimevalidator
- Silverstripe Recipe
- N/a — versions n/a
Weakness classification (CWE)
References
- cve@mitre.org (x_refsource_CONFIRM, Vendor Advisory)
Frequently asked questions
- What is CVE-2020-9309?
- CVE-2020-9309 is a high-severity vulnerability in Silverstripe Mimevalidator, classified under Unrestricted Upload of File with Dangerous Type. CVSS score: 8.8/10. Published 2020-07-15.
- How severe is CVE-2020-9309?
- High severity. CVSS v3 base score is 8.8 out of 10.