CVE-2020-27304

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

• CWE-23
• CWE-22

• 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

Published

Oct 21, 2021

Last Modified

Jun 17, 2026

Status

Modified

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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