CVE-2017-18887
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 · uneditedAn issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It discloses the team creator's e-mail address to members.
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 Server before versions 4.3.0, 4.2.1, and 4.1.2 contains an information disclosure vulnerability where the team creator's email address is improperly exposed to team members through the application interface or API, violating expected privacy boundaries.
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< 4.1.2>= 4.2.0, < 4.2.1= 4.3.0CVSS 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
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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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Locate the Mattermost Server versionAccess the System Console, then navigate to About > Mattermost. Alternatively, send a GET request to the /api/v4/system/analytics endpoint and look for the version field in the response.Affected if The installed version is not listed as fixed (4.1.2, 4.2.1, 4.3.0, or later)
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Compare against affected version rangesExamine the version number found in the previous step. Affected ranges are: any version less than 4.1.2; any version from 4.2.0 up to but not including 4.2.1; version 4.3.0 exactly.Affected if The installed version falls into any of these ranges: < 4.1.2, >= 4.2.0 and < 4.2.1, or equals 4.3.0
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Verify email disclosure through the UIAs a team member (not admin), navigate to the team menu and view the team member list. Check if the team creator's email address is visible in the member profile or team settings where it should not be exposed to regular team members.Affected if The team creator's email address is visible to non-admin team members in the interface
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Verify email disclosure through the APIUsing a regular team member account, query the team members endpoint via the API (such as /api/v4/teams/{team_id}/members or /api/v4/users/{user_id}) and inspect whether the team creator's email field is returned in the response.Affected if The API returns the team creator's email address in responses accessible to regular team members
The environment is affected if the installed Mattermost Server version is less than 4.1.2, between 4.2.0 and 4.2.1, or exactly 4.3.0, and the team creator email is visible to regular team members.
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 data4.1.24.2.1
Upgrade Mattermost Server to version 4.3.0, 4.2.1, 4.1.2 or later to receive the patched code that properly restricts team creator email address visibility.
- Consultation2.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-18887 — 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-2017-18887 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