CVE-2026-6345
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 versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail prevent disclosure of created user password which allows a malicious attacker to impersonate a user via the use of some of those passwords.. Mattermost Advisory ID: MMSA-2026-00614
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 versions 11.5.x through 11.5.1, 10.11.x through 10.11.13, and 11.4.x through 11.4.3 fail to prevent disclosure of user passwords during account creation, allowing authenticated attackers to obtain plaintext passwords and impersonate 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>= 10.11.0, < 10.11.14>= 11.4.0, < 11.4.4>= 11.5.0, < 11.5.2CVSS 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
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/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.
-
Determine installed Mattermost Server versionRun 'mattermost version' or check the system admin console under About > Mattermost, or inspect the version file typically at /opt/mattermost/version.txtAffected if The installed version falls within 10.11.0-10.11.13, 11.4.0-11.4.3, or 11.5.0-11.5.1
-
Identify authentication methods enabledNavigate to System Console > Authentication > Authentication Methods or inspect the config.json file for enablesigningwithemail, ldapenable, or samlenable settingsAffected if Email/password authentication (enable-sign-with-email) is enabled, as the vulnerability affects plaintext password disclosure during account creation
-
Verify account creation is accessibleCheck if user self-registration is allowed in System Console > Signup > Enable Account Creation, or review config.json for EnableUserAccess set to trueAffected if User account creation is permitted for authenticated attackers to exploit the flaw
-
Review audit logs for unexpected account creationSearch Mattermost audit logs (typically in /var/log/mattermost or via the admin UI) for entries with action='create_user' or similar, especially from unexpected users or IPsAffected if Audit logs show account creation events that were not initiated by legitimate administrators
You are affected if your Mattermost Server version is 10.11.x before 10.11.14, 11.4.x before 11.4.4, or 11.5.x before 11.5.2 AND email/password authentication with user account creation is enabled.
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 · scoped10.11.1411.4.411.5.2
Upgrade Mattermost to versions >11.5.1, >10.11.13, or >11.4.3 as specified in MMSA-2026-00614. Review audit logs for suspicious account creation activity.
Mattermost Server 10.11.14, 11.4.4, or 11.5.2 (or later stable releases within your major version)
- Backup your Mattermost database before starting the upgrade
- Upgrade Mattermost Server to version 10.11.14 (if on 10.11.x), 11.4.4 (if on 11.4.x), or 11.5.2 (if on 11.5.x)
- After upgrade, restart the Mattermost services
- Verify the upgrade was successful by checking the server version in the system console
- Test user login functionality to confirm the credential protection fix is working
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,416.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-6345 — 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-2026-6345 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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