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GitLabApplication

CVE-2021-39890

CRITICAL · 9.8 CVSS v3.1 Published 2021-12-06
Fix available
A fix is available. Upgrade to 14.1.7 / 14.2.5 or later.
See remediation →
100/100
Remediation priority · Urgent
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
It was possible to bypass 2FA for LDAP users and access some specific pages with Basic Authentication in GitLab 14.1.1 and above.

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 vulnerability in GitLab allowed LDAP users to bypass two-factor authentication (2FA) and access certain pages using Basic Authentication instead. This authentication bypass occurs because the application improperly validates LDAP-backed user sessions when 2FA is enforced, permitting access to protected resources without completing the second factor requirement.

MitigationUpgrade GitLab to the version that addresses this vulnerability (consult GitLab's security release for the specific patch version). For LDAP users, ensure 2FA policies are properly enforced and consider additional access controls while patches are applied.

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:>= 14.1.1, < 14.1.7>= 14.2.0, < 14.2.5= 14.3.0= 14.3.1

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

CVSS:3.1/AV:N/AC:L/PR:N/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. Determine installed GitLab version
    Run `sudo gitlab-rake gitlab:env:info` or check the version file at `/opt/gitlab/version` or `/usr/local/gitlab/version`. Alternatively, access Admin Area > Settings > General and scroll to 'GitLab version' at the bottom.
    Affected if The version falls within any of these ranges: 14.1.1 to 14.1.6, 14.2.0 to 14.2.4, 14.3.0, or 14.3.1.
  2. Verify LDAP authentication is enabled
    Check the GitLab configuration file `/etc/gitlab/gitlab.rb` for `gitlab_rails['ldap_enabled'] = true` or access Admin Area > LDAP Settings to confirm LDAP is configured as an authentication method.
    Affected if LDAP authentication is enabled and users can authenticate via LDAP.
  3. Confirm 2FA enforcement settings
    Navigate to Admin Area > Settings > General > Sign-up restrictions and verify whether 'Require two-factor authentication' is enabled. Also check Admin Area > Users to see if any users have 2FA enforced individually.
    Affected if Two-factor authentication is set as required or enforced for users.
  4. Check for Basic Authentication access attempts
    Review GitLab production logs at `/var/log/gitlab/gitlab-rails/production.log` for incoming requests using HTTP Basic Authentication headers on API or web endpoints, especially from LDAP user accounts. Use: `grep -i 'basic' /var/log/gitlab/gitlab-rails/production.log`.
    Affected if LDAP users are accessing GitLab via Basic Authentication without completing 2FA, indicated by successful authentication logs lacking 2FA verification events.

You are affected if your GitLab version is 14.1.1-14.1.6, 14.2.0-14.2.4, 14.3.0, or 14.3.1 AND you have LDAP authentication enabled with 2FA enforcement configured.

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

Upgrade GitLab to the version that addresses this vulnerability (consult GitLab's security release for the specific patch version). For LDAP users, ensure 2FA policies are properly enforced and consider additional access controls while patches are applied.

Recommended fix High confidence

14.1.7, 14.2.5, or 14.3.2+ (recommended: latest 14.3.x stable release)

  1. 1. Back up your GitLab instance database and configuration
  2. 2. Plan maintenance window - GitLab upgrade will require downtime
  3. 3. For GitLab 14.1.x: Upgrade to version 14.1.7 or later
  4. 4. For GitLab 14.2.x: Upgrade to version 14.2.5 or later
  5. 5. For GitLab 14.3.0-14.3.1: Upgrade to version 14.3.2 or later
  6. 6. After upgrade, verify LDAP users with 2FA enabled cannot bypass authentication
  7. 7. Test that Basic Authentication access controls work correctly for LDAP-integrated users
Caveat Patch releases within same minor version are low-risk, but review GitLab 14.3 release notes for any configuration or API changes

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

Fix this in GitLab Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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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-2021-39890 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