CVE-2020-27304

Name: CVE-2020-27304
Creator: NVD / NIST
Published: 2021-10-21T16:15:07.737+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 3.14%

Last modified Jun 17, 2026

CVE-2020-27304 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-based file upload mechanism, via the mg_handle_form_request API. Web applications that use the file upload form handler, and use parts of the user-controlled filename in the output path, are susceptible to directory traversal. EPSS estimates a 3.14% chance of exploitation in the next 30 days.

Description

The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-based file upload mechanism, via the mg_handle_form_request API. Web applications that use the file upload form handler, and use parts of the user-controlled filename in the output path, are susceptible to directory traversal

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.14%

86.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Civetweb Project	Civetweb	>= 1.8, < 1.15
Siemens	Sinec Infrastructure Network Services	< 1.0.1.1

References

https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfPatch, Third Party Advisory
https://groups.google.com/g/civetweb/c/yPBxNXdGgJQMailing List, Third Party Advisory
https://jfrog.com/blog/cve-2020-27304-rce-via-directory-traversal-in-civetweb-http-server/Exploit, Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdfPatch, Third Party Advisory
https://groups.google.com/g/civetweb/c/yPBxNXdGgJQMailing List, Third Party Advisory
https://jfrog.com/blog/cve-2020-27304-rce-via-directory-traversal-in-civetweb-http-server/Exploit, Third Party Advisory

Timeline

Published: Oct 21, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-27304?

How severe is CVE-2020-27304?

CVE-2020-27304 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 3.14% probability of exploitation in the next 30 days.

How do I fix CVE-2020-27304?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-27304?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST