CVE-2023-3920Public exploitNetwork attack vector

Unauthorized fork linkage via missing role enforcement

Published Sep 29, 2023 · Updated Aug 14, 2026

Incorrect authorization in affected GitLab versions allows remote authenticated users to create unauthorized fork relationships. The create-fork-relationship API accepts a Maintainer's authenticated POST request without enforcing its Owner-or-administrator authorization requirement. Maintainer access to the downstream project and access to an upstream project are sufficient to alter the fork topology, including by linking to a public project.

CVSS severity4.3
Medium
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in affected GitLab versions allows remote authenticated users to create unauthorized fork relationships. The create-fork-relationship API accepts a Maintainer's authenticated POST request without enforcing its Owner-or-administrator authorization requirement. Maintainer access to the downstream project and access to an upstream project are sufficient to alter the fork topology, including by linking to a public project.

The record

CVE
CVE-2023-3920
Published
Sep 29, 2023
Updated
Aug 14, 2026
Vendor
GitLab
Product
GitLab
Classifications
CWE-863
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 29, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 14, 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=11.2 <16.2.8
  2. Affected versionversion=16.3 <16.3.5
  3. Affected versionversion=16.4 <16.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=11.2 <16.2.8; version=16.3 <16.3.5; version=16.4 <16.4.1

Published CVSS scores

4.3GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/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 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-863Incorrect Authorization

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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