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GitLabApplication

CVE-2023-3900

HIGH · 7.5 CVSS v3.1 Published 2023-08-02
Fix available
A fix is available. Upgrade to 16.1.3 / 16.2.2 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An issue has been discovered in GitLab CE/EE affecting all versions starting from 16.1 before 16.1.3, all versions starting from 16.2 before 16.2.2. An invalid 'start_sha' value on merge requests page may lead to Denial of Service as Changes tab would not load.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

An input validation vulnerability in GitLab CE/EE allows attackers to cause a Denial of Service by providing an invalid 'start_sha' parameter value on merge request pages, causing the Changes tab to fail to load.

MitigationUpgrade GitLab to version 16.1.3, 16.2.2, or later. Alternatively, implement input validation for the start_sha parameter to reject malformed or invalid SHA values before processing.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
GitLabApplication
Affected:>= 16.1, < 16.1.3>= 16.2, < 16.2.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed GitLab version
    Run command: gitlab-rake gitlab:env:info or check the GitLab admin panel under /admin/application_settings/general for the version number
    Affected if The version is 16.1.0, 16.1.1, or 16.1.2; OR 16.2.0 or 16.2.1 (falls within 16.1 <= version < 16.1.3 or 16.2 <= version < 16.2.2)
  2. Confirm Merge Request module is enabled
    Verify that the GitLab instance has the Merge Requests feature enabled. Check in Admin Area under Settings > General > Visibility and access controls, or attempt to access any project and navigate to the Merge Requests section
    Affected if Merge Requests are accessible and the instance is running an affected version from step 1
  3. Test the start_sha parameter on a merge request
    Open any existing merge request in the browser and modify the URL to include an invalid start_sha value, for example: /merge_requests/1?start_sha=invalid_sha or /merge_requests/1?start_sha= (empty value) and attempt to view the Changes tab
    Affected if The Changes tab fails to load or returns an error, indicating the vulnerability is present and exploitable

The environment is affected if GitLab version is 16.1.0-16.1.2 or 16.2.0-16.2.1 AND the Merge Requests feature is enabled, as invalid start_sha parameter values will cause the Changes tab to fail.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 16.1.3 / 16.2.2 or later
Fixed in 16.1.316.2.2
Interim mitigation

Upgrade GitLab to version 16.1.3, 16.2.2, or later. Alternatively, implement input validation for the start_sha parameter to reject malformed or invalid SHA values before processing.

Recommended fix High confidence

16.1.3, 16.2.2, or later (preferably latest stable 16.x release)

  1. 1. Schedule a maintenance window for the GitLab upgrade
  2. 2. Back up the GitLab database and repositories
  3. 3. For GitLab 16.1.x installations: upgrade to version 16.1.3 or later
  4. 4. For GitLab 16.2.x installations: upgrade to version 16.2.2 or later
  5. 5. For best security posture, upgrade to the latest stable release (currently 16.11 or later)
  6. 6. After upgrade, verify the Changes tab on merge requests loads correctly with various start_sha values
Caveat Standard GitLab upgrade considerations apply - review release notes for breaking changes between minor versions

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in GitLab Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA2.0 h
20.0 hours of engineering $3,500
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-3900 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data