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Public proof of conceptFix available

CVE-2020-27386

A public proof of concept exists; no exploitation attested.

  • Published2020-11-12
  • Fixed in1.5.9
  • WeaknessCWE-434

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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>.

Timeline

dates in UTC
  1. 2020-11-1219:15CVE publishedNVD

Versions per branch

NVD
Flexdotnetcms project flexdotnetcms
BranchAffectedFixed in
1.5< 1.5.91.5.9

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Flexdotnetcms project flexdotnetcms to 1.5.9

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
1 moduleexploit/windows/http/flexdotnetcms_upload_execrank: excellentModule metadata: Metasploit Framework, © Rapid7, Inc., BSD-3-Clause.
Metasploit Framework

Sources

  • NVDCVSS 3.18.8read 2026-10-23
  • NVDCVSS 2.06.5read 2026-10-23
  • NVDweakness (CWE)CWE-434read 2026-10-23
  • FIRST EPSSEPSS score72.1 %read 2026-11-04
  • Metasploit FrameworkMetasploit modules1known since 2026-11-01

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Published
2020-11-12
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2020-27386?

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>.

Is CVE-2020-27386 actively exploited?

Active exploitation of CVE-2020-27386 has not been confirmed. Its EPSS score was 72.1% on 2026-11-04, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2020-27386?

CVE-2020-27386 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

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