CVE-2026-23721Network attack vector

Authenticated group-membership disclosure via cross-project permission check

Published Jan 19, 2026 · Updated Jan 19, 2026

Missing authorization in OpenProject 16.6.4 and earlier and 17.0.0 allows remote authenticated users to disclose group memberships. The group-membership permission check accepts View Members permission in any project instead of requiring that permission where the target group is a member. Any account holding that permission in one project can enumerate every group and identify its users, but cannot modify memberships through this flaw.

CVSS severity4.3
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in OpenProject 16.6.4 and earlier and 17.0.0 allows remote authenticated users to disclose group memberships. The group-membership permission check accepts View Members permission in any project instead of requiring that permission where the target group is a member. Any account holding that permission in one project can enumerate every group and identify its users, but cannot modify memberships through this flaw.

The record

CVE
CVE-2026-23721
Published
Jan 19, 2026
Updated
Jan 19, 2026
Vendor
OpenProject GmbH
Product
OpenProject
Classifications
CWE-862, T1087
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jan 19, 2026Record 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=< 16.6.5
  2. Affected versionversion== 17.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OpenProject GmbH · OpenProjectversion=< 16.6.5; version== 17.0.0

Published CVSS scores

4.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-862Missing Authorization
T1087Account Discovery

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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