CVE-2021-37862
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 · uneditedMattermost 6.0 and earlier fails to sufficiently validate the email address during registration, which allows attackers to trick users into signing up using attacker-controlled email addresses via crafted invitation token.
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 confidenceMattermost 6.0 and earlier has insufficient email address validation during the user registration process when processing invitation tokens. Attackers can craft malicious invitation tokens to bypass validation and register accounts with attacker-controlled email addresses, potentially enabling account takeover or phishing attacks against legitimate users.
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<= 6.0CVSS 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
- Required
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/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 Mattermost Server versionAccess the Mattermost System Console or check the server configuration. Navigate to About > Mattermost or run `grep -i version /opt/mattermost/version.go` (path may vary based on installation)Affected if The installed version is 6.0 or earlier (any version up to and including 6.0)
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Confirm invitation token registration is enabledNavigate to System Console > Users and Teams > Invitations or check configuration file (config.json) for 'EnableEmailInvitations' or 'EnableSignUpWithEmail' settingsAffected if Email-based registration or invitation tokens are enabled (the vulnerability applies to environments allowing user registration via invitation tokens)
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Review recent user registrationsQuery the Users table in the Mattermost database for accounts created within the vulnerability window, or review System Console logs for user creation events around the time of potential exploitationAffected if New user accounts exist with email addresses that do not match expected organizational domains or appear suspicious
You are affected if Mattermost Server version is 6.0 or earlier AND email-based invitation/registration is enabled, requiring further investigation of recent user registrations for suspicious activity.
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.
dbcve · scopedUpgrade to Mattermost 6.1 or later which contains proper email validation fixes. Review recent user registrations for suspicious activity and invalidate any potentially crafted invitation tokens.
Mattermost Server 6.3.x or later (any version > 6.0)
- 1. Back up your current Mattermost Server data and configuration.
- 2. Download and install the latest stable Mattermost Server version (recommended: 6.3.x or later).
- 3. Verify that the email validation during invitation token registration is working correctly by testing with crafted invitation tokens.
- 4. Confirm that the server starts without errors and all services are正常运行.
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-37862 — 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-2021-37862 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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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.
- 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