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GitLabApplication

CVE-2021-39867

HIGH · 8.1 CVSS v3.1 Published 2021-10-05
Fix available
A fix is available. Upgrade to 14.1.7 / 14.2.5 or later.
See remediation →
87/100
Remediation priority · High
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
In all versions of GitLab CE/EE since version 8.15, a DNS rebinding vulnerability in Gitea Importer may be exploited by an attacker to trigger Server Side Request Forgery (SSRF) attacks.

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 · moderate confidence

A DNS rebinding vulnerability in the Gitea Importer component of GitLab allows attackers to bypass host-based restrictions by exploiting the timing gap between DNS resolution and HTTP requests, enabling SSRF attacks against internal services.

MitigationImplement DNS rebinding protections in the Gitea Importer, including strict host allowlisting, DNS cache disabling, and request timeout controls to prevent attackers from directing the server to internal or unauthorized endpoints.

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:>= 8.15.0, < 14.1.7>= 14.2.0, < 14.2.5= 4.3.0

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
None

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

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. Determine installed GitLab version
    Run command: `cat /opt/gitlab/version` or `gitlab-rake gitlab:env:info` to display the installed GitLab version. Alternatively, check the Admin Area > Settings > General page for the version number.
    Affected if The displayed version falls within >= 8.15.0 and < 14.1.7, OR >= 14.2.0 and < 14.2.5, OR equals 4.3.0
  2. Check if Gitea Importer is accessible
    Navigate to the project import page in GitLab (New Project > Import project) and verify if the Gitea Importer option is listed or enabled in the Admin Area > Settings > General > Import sources settings.
    Affected if The Gitea Importer import source is enabled or available in the instance
  3. Verify Gitea import functionality is used
    Review project imports via Admin Area > Projects > Filter by import type, or check the database table `import_data` for recent imports using the Gitea source.
    Affected if Any projects have been imported using the Gitea Importer within the affected version timeframe

The environment is affected if GitLab version falls within the vulnerable ranges AND the Gitea Importer feature is enabled or has been used, allowing potential SSRF via DNS rebinding attacks against internal services.

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 14.1.7 / 14.2.5 or later
Fixed in 14.1.714.2.5
Interim mitigation

Implement DNS rebinding protections in the Gitea Importer, including strict host allowlisting, DNS cache disabling, and request timeout controls to prevent attackers from directing the server to internal or unauthorized endpoints.

Recommended fix High confidence

14.1.7 for 14.1.x; 14.2.5 for 14.2.x; 14.3.0+ for versions >= 14.3.0

  1. Backup your GitLab instance data and database before upgrading
  2. Determine your current GitLab version in Admin Area > Overview > Instances
  3. If running GitLab 14.1.x (>= 14.1.0), upgrade to version 14.1.7
  4. If running GitLab 14.2.x (>= 14.2.0), upgrade to version 14.2.5
  5. If running GitLab 14.3.0 or later, no action needed - vulnerability is fixed
  6. Follow the official upgrade path for your installation method (Omnibus, source, or Docker) at https://docs.gitlab.com/ee/update/
  7. After upgrade, verify the Gitea Importer functionality in Project > Import > Gitea works correctly
Caveat Review GitLab release notes for version-specific breaking changes before upgrading

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
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2021-39867 in production — separate from our analysis above.

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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