What’s Vulnerable › Vulnerabilities

CVE-2020-27386

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 72.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-11-12 · updated 2026-06-17
• Weakness: CWE-434

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 /<path_to_file>.

Affected products

• Flexdotnetcms Project Flexdotnetcms: before 1.5.9 — fixed in 1.5.9

How to fix

Upgrade to a fixed version: Flexdotnetcms Project Flexdotnetcms 1.5.9. Check the vendor advisory for mitigations.

References

• http://packetstormsecurity.com/files/160411/FlexDotnetCMS-1.5.8-Arbitrary-ASP-File-Upload.html
• https://blog.vonahi.io/whats-in-a-re-name/
• https://github.com/MacdonaldRobinson/FlexDotnetCMS/releases/tag/v1.5.9
• https://github.com/rapid7/metasploit-framework/pull/14339
• http://packetstormsecurity.com/files/160411/FlexDotnetCMS-1.5.8-Arbitrary-ASP-File-Upload.html
• https://blog.vonahi.io/whats-in-a-re-name/
• https://github.com/MacdonaldRobinson/FlexDotnetCMS/releases/tag/v1.5.9
• https://github.com/rapid7/metasploit-framework/pull/14339

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