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GitLabApplication

CVE-2023-5356

HIGH · 8.8 CVSS v3.1 Published 2024-01-12
Fix available
A fix is available. Upgrade to 16.5.6 / 16.6.4 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable 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
Incorrect authorization checks in GitLab CE/EE from all versions starting from 8.13 before 16.5.6, all versions starting from 16.6 before 16.6.4, all versions starting from 16.7 before 16.7.2, allows a user to abuse slack/mattermost integrations to execute slash commands as another user.

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

Incorrect authorization checks in GitLab's slack/mattermost integration allow an authenticated user to execute slash commands as another user by abusing the integration's command processing. This is a broken access control vulnerability where the system fails to properly validate the requesting user's identity when relaying commands through external integrations.

MitigationUpgrade GitLab to version 16.5.6, 16.6.4, 16.7.2 or later to receive the authorization fix. Prioritize this for instances with slack/mattermost integrations enabled.

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:>= 8.13.0, < 16.5.6>= 16.6.0, < 16.6.4= 16.7.0= 16.7.1

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. Check installed GitLab version
    Run `sudo gitlab-rake gitlab:version` or check the GitLab admin panel under /admin/about to see the exact version number
    Affected if The version falls within >= 8.13.0 and < 16.5.6, OR >= 16.6.0 and < 16.6.4, OR equals 16.7.0 or 16.7.1
  2. Verify slack integration status
    Navigate to GitLab admin settings: go to Admin Area > Settings > Integrations > Slack, or check via API at /api/v4/integrations with Slack as the name. Confirm whether the Slack integration is enabled.
    Affected if The Slack integration is enabled and active in the GitLab instance
  3. Verify mattermost integration status
    Navigate to GitLab admin settings: go to Admin Area > Settings > Integrations > Mattermost, or check via API at /api/v4/integrations with Mattermost as the name. Confirm whether the Mattermost integration is enabled.
    Affected if The Mattermost integration is enabled and active in the GitLab instance

The environment is affected if GitLab version is in the vulnerable range AND either the Slack or Mattermost integration is enabled.

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 16.5.6 / 16.6.4 or later
Fixed in 16.5.616.6.4
Interim mitigation

Upgrade GitLab to version 16.5.6, 16.6.4, 16.7.2 or later to receive the authorization fix. Prioritize this for instances with slack/mattermost integrations enabled.

Recommended fix High confidence

Upgrade to GitLab 16.7.2 or later (or 16.6.4+ / 16.5.6+ if staying on older major branches)

  1. 1. Back up your GitLab instance data before proceeding with the upgrade
  2. 2. Review the GitLab upgrade documentation for your installation method (package, source, Helm chart, etc.)
  3. 3. Plan for appropriate maintenance window as upgrade may require downtime
  4. 4. For GitLab installations using omnibus packages: run 'apt-get update && apt-get install gitlab-ce' (or 'gitlab-ee') to upgrade to the latest fixed version
  5. 5. For source installations: stop GitLab services, download the fixed release (16.7.2 or later), replace source files, run database migrations, and restart services
  6. 6. After upgrade, verify the GitLab version matches a fixed release (16.5.6+, 16.6.4+, or 16.7.2+)
  7. 7. Test that slash commands via Slack/Mattermost integrations work correctly with proper authorization
Caveat Major GitLab upgrades may require database migrations and can have breaking changes; review GitLab release notes for your upgrade path

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

Fix this in GitLab Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2023-5356 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