CVE-2023-3979Public exploitNetwork attack vector

Persistent branch write access via stale collaboration authorization

Published Sep 29, 2023 · Updated Aug 14, 2026

Incorrect authorization in affected GitLab versions allows remote authenticated users to retain merge-request source-branch write access. An upstream Developer can open a merge request from a non-protected source branch to an attacker-controlled public fork, enable collaboration, and retain delegated write permission after project membership is revoked. The attack requires prior Developer access, public projects, restricted merge-request visibility on the fork, and an open collaboration-enabled merge request; it permits source-code modification but not protected-branch writes.

CVSS severity3.1
Low
EPSS probability0.40%
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 retain merge-request source-branch write access. An upstream Developer can open a merge request from a non-protected source branch to an attacker-controlled public fork, enable collaboration, and retain delegated write permission after project membership is revoked. The attack requires prior Developer access, public projects, restricted merge-request visibility on the fork, and an open collaboration-enabled merge request; it permits source-code modification but not protected-branch writes.

The record

CVE
CVE-2023-3979
Published
Sep 29, 2023
Updated
Aug 14, 2026
Vendor
GitLab
Product
GitLab
Classifications
CWE-863, T1098
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=10.6 <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=10.6 <16.2.8; version=16.3 <16.3.5; version=16.4 <16.4.1

Published CVSS scores

3.1GitLab Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
4.3NIST NVDCVSS: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 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 exploitPublished

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1098Account Manipulation

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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