CVE-2017-18905
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 4.0.0, 3.10.2, and 3.9.2, when used as an OAuth 2.0 service provider, Session invalidation was mishandled.
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 4.0.0, 3.10.2, and 3.9.2 mishandles session invalidation when the server is used as an OAuth 2.0 service provider, potentially allowing authenticated sessions to persist beyond their intended lifetime.
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< 3.9.2>= 3.10.0, < 3.10.2CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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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Determine Mattermost Server versionRun the command: `mattermost server --version` or check the version displayed in the system console under About > Mattermost. Alternatively, check the binary or package version installed on the system.Affected if The installed version is less than 3.9.2, or greater than or equal to 3.10.0 but less than 3.10.2, or less than 4.0.0.
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Identify if OAuth 2.0 service provider is configuredLog in to the Mattermost System Console and navigate to OAuth 2.0 > OAuth 2.0 Service Provider. Check whether Enable OAuth 2.0 Service Provider is set to true. Alternatively, inspect the configuration file (config.json) for the "OAuthSettings" -> "EnableOAuthService" setting.Affected if OAuth 2.0 Service Provider is enabled (set to true).
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Review active OAuth authorization tokensQuery the database for active OAuth sessions. Connect to the Mattermost database and run: SELECT * FROM oauth_access_tokens WHERE expires_at > NOW(); or inspect tokens via the API endpoint /api/v4/oauth/access_tokens if accessible with admin credentials.Affected if There are OAuth access tokens present with expiration times that have passed or appear to be lingering beyond their expected lifetime.
You are affected if your Mattermost Server version is below 3.9.2, between 3.10.0 and 3.10.2, or below 4.0.0, AND you have OAuth 2.0 Service Provider 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.
From vendor data3.9.23.10.2
Upgrade Mattermost Server to version 4.0.0, 3.10.2, 3.9.2 or later. If immediate upgrade is not possible, review and manually revoke active OAuth sessions.
- Consultation2.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-18905 — 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-2017-18905 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
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