CVE-2023-4478
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 fails to restrict which parameters' values it takes from the request during signup allowing an attacker to register users as inactive, thus blocking them from later accessing Mattermost without the system admin activating their accounts.
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 confidenceMattermost's user registration endpoint does not properly validate or restrict incoming request parameters, allowing an attacker to manipulate the 'inactive' parameter during signup. This creates user accounts that are marked as inactive, preventing those users from logging in without manual system admin intervention.
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< 7.8.9>= 7.9.0, < 7.10.5= 8.0.0CVSS 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
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify Mattermost Server versionRun 'grep -i version /opt/mattermost/config/config.json' or check the system admin console under About > Mattermost, or use the CLI: 'mattermost version'Affected if The installed version falls into any of these ranges: < 7.8.9, >= 7.9.0 and < 7.10.5, or exactly 8.0.0
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Confirm user registration is enabledNavigate to System Console > User Authentication > Signup or inspect the config file at /opt/mattermost/config/config.json for 'EnableSignUp' and 'EnableEmailInvitations' settings set to trueAffected if User self-registration or email invitation signup is currently enabled, allowing external attackers to reach the vulnerable registration endpoint
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Review user accounts for suspicious inactive statusRun CLI command 'mattermost user list --field email --field lastactive --field inactive' or query the database: 'SELECT Username, Email, CreateAt, DeleteAt FROM Users WHERE DeleteAt > 0 OR LastActivityAt IS NULL' to identify inactive accountsAffected if There are unexpectedly created inactive user accounts that were not intentionally created by administrators or were never activated through email verification
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Inspect registration logs for the inactive parameterSearch Mattermost logs (typically in /var/log/mattermost/ or via 'mattermost logs') for POST requests to /api/v4/users containing 'inactive' in the request body, or enable DEBUG logging to capture request parametersAffected if Log entries show registration requests with the 'inactive' parameter present in the request payload
Your environment is affected if Mattermost Server version is in the affected range AND user registration is currently enabled, allowing attackers to create inactive accounts via the signup endpoint.
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 · scoped7.8.97.10.5
Apply the vendor patch from Mattermost for this vulnerability; until patched, monitor registration endpoints for anomalous requests with the 'inactive' parameter set.
Upgrade to 7.8.9 (for 7.8.x), 7.10.5 (for 7.9.x-7.10.x), or 8.0.1 (for 8.0.0) - or migrate to the latest stable release (8.1.x or later)
- 1. Identify the currently running Mattermost Server version by checking the system console or running 'mattermost version'
- 2. Determine which upgrade path applies based on current version: if running 7.8.x, upgrade to 7.8.9; if running 7.9.x or 7.10.x, upgrade to 7.10.5; if running 8.0.0, upgrade to 8.0.1
- 3. Before upgrading, backup the Mattermost database and configuration files
- 4. Download the appropriate fixed version from the official Mattermost downloads page (mattermost.com)
- 5. Follow Mattermost's standard upgrade documentation for your deployment method (e.g., sudo apt-get upgrade or yum update for Omnibus, or manual upgrade for other methods)
- 6. After upgrade, verify the server starts successfully and test user registration functionality
- 7. Review user list in the system console to confirm no unauthorized inactive users were created during the vulnerability window
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-4478 — 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-2023-4478 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
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