CVE-2017-20028Public exploitNetwork attack vector

Remote code execution via unrestricted post attachment upload

Published Jun 9, 2022 · Updated Apr 15, 2025

Unrestricted file upload in HumHub 0.20.1 and 1.0.0-beta.3 allows remote authenticated users to execute PHP on the server. The post composer upload endpoint accepts arbitrary extensions, so a PHP attachment under the web root executes when upload-directory protections are not enforced. An account and a server that does not honor the supplied .htaccess protection are required; registration and every file type are allowed by default.

CVSS severity5.6
Medium
EPSS probability0.81%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Unrestricted file upload in HumHub 0.20.1 and 1.0.0-beta.3 allows remote authenticated users to execute PHP on the server. The post composer upload endpoint accepts arbitrary extensions, so a PHP attachment under the web root executes when upload-directory protections are not enforced. An account and a server that does not honor the supplied .htaccess protection are required; registration and every file type are allowed by default.

The record

CVE
CVE-2017-20028
Published
Jun 9, 2022
Updated
Apr 15, 2025
Vendor
HumHub GmbH & Co. KG
Product
HumHub
Classifications
CWE-269, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 9, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.20.1
  2. Affected versionversion=1.0.0-beta.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

HumHub GmbH & Co. KG · HumHubversion=0.20.1; version=1.0.0-beta.3

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
5.6VulDB CNACVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.6Curesec Research TeamAV:N/AC:H/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-269Improper Privilege Management
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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