CVE-2021-37156
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 · uneditedRedmine 4.2.0 and 4.2.1 allow existing user sessions to continue upon enabling two-factor authentication for the user's account, but the intended behavior is for those sessions to be terminated.
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 confidenceIn Redmine 4.2.0 and 4.2.1, when a user enables two-factor authentication for their account, existing sessions remain valid instead of being terminated as intended. This allows authenticated sessions established with only username/password to continue accessing the account without requiring the newly configured second factor.
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= 4.2.0= 4.2.1CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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 checksWork through these to decide whether this CVE applies to you.
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Identify Redmine versionCheck the version.rb file in the Redmine installation directory, or access /admin/info page if you have admin access, or run 'ruby bin/rails runner "puts Redmine::VERSION::STRING"' from the Redmine root directoryAffected if Version is exactly 4.2.0 or 4.2.1
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Confirm Two-Factor Authentication is availableCheck if the two_factor_authentication plugin exists in the plugins directory or inspect the authentication methods available in the Redmine administration panel under Settings > AuthenticationAffected if 2FA plugin is installed and enabled in the system
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Identify users with 2FA enabledQuery the users table for records where two_factor_authentication is enabled, or use the admin interface to list users with 2FA active. The relevant column is typically 'two_factor_auth' or similar in the databaseAffected if Any user accounts have 2FA enabled in versions 4.2.0 or 4.2.1 - these accounts had sessions that were not invalidated when 2FA was configured
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Check for stale active sessionsInspect the sessions table or token storage in the database for active sessions that were created before 2FA was enabled on the associated user accountAffected if Active sessions exist for users who later enabled 2FA - these sessions can authenticate without providing the second factor
You are affected if running Redmine version 4.2.0 or 4.2.1 and any user in your system has enabled Two-Factor Authentication, as their pre-2FA sessions remain valid and do not require the second factor for authentication.
Generated from the published advisory. Verify against your own configuration.
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.
From vendor dataAdminister a patch from Redmine that properly invalidates existing sessions when 2FA is enabled, or manually invalidate sessions/administratively reset affected user accounts until upgrade is possible.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-37156 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-37156 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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