CVE-2020-27386
HighPublic exploitAn unrestricted file upload issue in FlexDotnetCMS before v1.5.9 allows an authenticated remote attacker to upload and execute arbitrary files by using the FileManager to upload malicious code (e.g., ASP code) in the form of a safe file type (e.g., a TXT file), and then using…
Published Nov 12, 2020 · Updated Jul 8, 2026
Key Facts
Patch immediately- CVE-2020-27386 is a high-severity vulnerability (CVSS 8.8 v3.1) affecting Flexdotnetcms (Flexdotnetcms Project).
- It is not listed in any known-exploited vulnerabilities catalog. Public exploit code is available.
- EPSS estimates a 73% probability of exploitation in the next 30 days.
- Fixed versions are available, including Flexdotnetcms 1.5.9.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
8.8
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
73%
Higher than 99.4% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
Available
Proof-of-concept or weaponized module
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Description
An unrestricted file upload issue in FlexDotnetCMS before v1.5.9 allows an authenticated remote attacker to upload and execute arbitrary files by using the FileManager to upload malicious code (e.g., ASP code) in the form of a safe file type (e.g., a TXT file), and then using the FileEditor (in v1.5.8 and prior) or the FileManager's rename function (in v1.5.7 and prior) to rename the file to an executable extension (e.g., ASP), and finally executing the file via an HTTP GET request to /.
Affected Products
1 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| FlexdotnetcmsFlexdotnetcms Project | See advisory | 1.5.9 |
Patched Releases
Flexdotnetcms
1.5.9
Timeline
Publicly disclosed
Nov 12, 2020
Last updated
Jul 8, 2026
Weakness Type
- CWE-434 Unrestricted Upload of File with Dangerous Type
References
- advisoryhttp://packetstormsecurity.com/files/160411/FlexDotnetCMS-1.5.8-Arbitrary-ASP-File-Upload.html
- advisoryhttps://github.com/MacdonaldRobinson/FlexDotnetCMS/releases/tag/v1.5.9
- patchhttps://github.com/rapid7/metasploit-framework/pull/14339
- exploithttps://blog.vonahi.io/whats-in-a-re-name/
- exploitMSF flexdotnetcms_upload_exec.rb
FAQ
Common Questions.
An unrestricted file upload issue in FlexDotnetCMS before v1.5.9 allows an authenticated remote attacker to upload and execute arbitrary files by using the FileManager to upload malicious code (e.g., ASP code) in the form of a safe file type (e.g., a TXT file), and then using the FileEditor (in v1.5.8 and prior) or th…
Affected: Flexdotnetcms (Flexdotnetcms Project). The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
Public exploit code is available.
Fixed versions are available, including Flexdotnetcms 1.5.9.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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