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ElabftwApplication

CVE-2021-43834

CRITICAL · 9.8 CVSS v3.1 Published 2021-12-16
Fix available
A fix is available. Upgrade to 4.2.0 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
eLabFTW is an electronic lab notebook manager for research teams. In versions prior to 4.2.0 there is a vulnerability which allows an attacker to authenticate as an existing user, if that user was created using a single sign-on authentication option such as LDAP or SAML. It impacts instances where LDAP or SAML is used for authentication instead of the (default) local password mechanism. Users should upgrade to at least version 4.2.0.

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

eLabFTW versions before 4.2.0 contain an authentication bypass vulnerability in the SSO authentication flow (LDAP/SAML). Attackers can impersonate existing users who were created via SSO login by exploiting improper validation in the authentication mechanism, achieving unauthorized access without knowing the user's credentials.

MitigationUpgrade eLabFTW to version 4.2.0 or later. Until then, consider disabling SSO authentication methods and using local password authentication only, or implement additional access controls on affected instances.

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
ElabftwApplication
Affected:< 4.2.0

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
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. Identify installed eLabFTW version
    Access the admin dashboard or check the version file in the installation directory. The version is typically visible in the footer of web pages or via the admin panel.
    Affected if The installed version is any version before 4.2.0 (e.g., 4.1.x, 4.0.x, earlier releases).
  2. Determine if LDAP authentication is enabled
    Review the eLabFTW configuration files or access the 'Authentication' section in the admin panel to check whether LDAP integration is configured and active.
    Affected if LDAP authentication method is enabled and in use on the instance.
  3. Determine if SAML authentication is enabled
    Review the eLabFTW configuration files or access the 'Authentication' section in the admin panel to check whether SAML single sign-on is configured and active.
    Affected if SAML authentication method is enabled and in use on the instance.
  4. Identify users created via SSO login
    Query the user database or user management interface to identify accounts that were created through LDAP or SAML authentication flows (typically indicated by authentication source field).
    Affected if Any user accounts exist that were created via LDAP or SAML login, as these accounts could be impersonated through the vulnerability.

You are affected if your eLabFTW installation version is below 4.2.0 AND you have LDAP or SAML authentication enabled with SSO-created user accounts present.

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 4.2.0 or later
Fixed in 4.2.0
Interim mitigation

Upgrade eLabFTW to version 4.2.0 or later. Until then, consider disabling SSO authentication methods and using local password authentication only, or implement additional access controls on affected instances.

Recommended fix High confidence

4.2.0

  1. 1. Back up the current eLabFTW installation and database before proceeding with any upgrade.
  2. 2. Consult the official eLabFTW upgrade documentation for your specific installation method (Docker, manual, or package manager).
  3. 3. Upgrade eLabFTW to version 4.2.0 or later using the appropriate method for your deployment.
  4. 4. After upgrade, verify that the authentication mechanism is functioning correctly for all user types, especially LDAP and SAML users.
  5. 5. Confirm the installed version matches or exceeds 4.2.0 by checking the admin panel or using the CLI tools.

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

Fix this in Elabftw Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing8.0 h
  • Review / QA3.0 h
20.0 hours of engineering $3,420
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,472.

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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-2021-43834 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