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).
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.84%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- EPSS
- 1.84% probability · 79th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-434
- Affected
- silverstripe/mimevalidator · silverstripe/recipe
- Source
- cve@mitre.org
EPSS 1.8% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.