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Fencer Intel
critical 9.8

CVE-2020-27304 json

The CivetWeb web library does not validate uploaded filepaths when running on an OS other than Windows, when using the built-in HTTP form-b…

published 5y ago modified 4mo ago also EUVD-2020-19817

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.3%
EPSS 3.3% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

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

Patch / fix

  • civetweb_project civetweb 1.15
  • siemens sinec_infrastructure_network_services 1.0.1.1
  • civetweb Debian 14, Debian 13, Debian 12 1.15+dfsg-1

debian advisories DEBIAN-CVE-2020-27304

  • civetweb openSUSE Leap 15.2 1.15-lp152.2.3.1

opensuse advisories openSUSE-SU-2021:1424-1

  • ceph Azure Linux 3.0 18.2.1-1

azure linux advisories AZL-39076

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-27304 updated cvss 9.8

civetweb: directory traversal when using the built-in example HTTP form-based file upload mechanism via the mg_handle_form_request API

  • Red Hat Ceph Storage 2 ceph, librbd1, librgw2, ceph-mds, ceph-mon, ceph-osd, +12 more Red Hat Ceph Storage 3 ceph, librbd1, librgw2, ceph-mds, ceph-mgr, ceph-mon, +15 more
    affected: no fix planned “Will not fix”
  • Red Hat RHACS 3.67 for RHEL 8 advanced-cluster-security/rhacs-rhel8-operator 3.67.0-3
    fixed: vendor fix RHSA-2021:4902
  • Red Hat RHACS 3.67 for RHEL 8 advanced-cluster-security/rhacs-operator-bundle 3.67.0-2
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

cisa ICSA-22-167-09 updated cvss 9.8

Siemens SCALANCE LPE9403 Third-Party Vulnerabilities

Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf

Exploit prediction

3.27% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • jfrog.com https://jfrog.com/blog/cve-2020-27304-rce-via-directory-traversal-in-civetweb-http-server/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • civetweb_project civetweb

Classification

Weakness
  • CWE-23 Relative Path Traversal
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Intel 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.