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Fencer Vulns
high 8.8

CVE-2020-27386 in the critical feed json

An unrestricted file upload issue in FlexDotnetCMS before v1.5.9 allows an authenticated remote attacker to upload and execute arbitrary fi…

published 2020-11-12 5 y ago modified 2026-06-17 4 mo ago also EUVD-2020-19898

cvss
8.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
71.6%
EPSS 71.6% chance of exploitation in 30 days, percentile 99.4%
public exploits
1
Metasploit

Summary

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>.

Patch / fix

  • flexdotnetcms_project flexdotnetcms 1.5.9

Timeline

  1. First public exploit (Metasploit exploit/windows/http/flexdotnetcms_upload_exec)
  2. Published

Exploit prediction

71.57% chance of exploitation in the next 30 days, higher than 99.4% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

CVSS scores

assigned by version score vector
NVD 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P

Classification

Weakness
  • CWE-434 Unrestricted Upload of File with Dangerous Type

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.