CVE-2025-9084
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 10.5.x <= 10.5.9 fail to properly validate redirect URLs which allows attackers to redirect users to malicious sites via crafted OAuth login URLs
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 versions 10.5.x through 10.5.9 contain an open redirect vulnerability in the OAuth login flow where redirect URLs are not properly validated, allowing attackers to craft malicious OAuth login URLs that redirect authenticated users to external malicious sites after the OAuth process completes.
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>= 10.5.0, < 10.5.10CVSS 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
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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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Check installed Mattermost Server versionRun 'mattermost version' or check the About section in the System Console, or inspect the version file in the Mattermost installation directoryAffected if The installed version is 10.5.0 through 10.5.9 inclusive
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Verify OAuth sign-in is enabledNavigate to System Console > Authentication > OAuth 2.0 (or check config.json for 'EnableOAuth' settings)Affected if OAuth 2.0 authentication is enabled (the vulnerability only applies when OAuth login is active)
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Identify configured OAuth providersCheck System Console > Authentication > OAuth 2.0 for any configured providers (GitLab, Google, Office 365, etc.) or inspect config.json for OAuth provider entriesAffected if At least one OAuth provider is configured and enabled
You are affected if Mattermost Server is version 10.5.0-10.5.9 AND OAuth authentication is enabled with at least one configured provider.
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 · scoped10.5.10
Upgrade to Mattermost version 10.5.10 or later which implements proper redirect URL validation using an explicit allowlist of permitted domains for OAuth callbacks.
Mattermost Server 10.5.10 or later
- 1. Back up your Mattermost Server database and configuration files.
- 2. Download Mattermost Server version 10.5.10 or later from the official Mattermost downloads page.
- 3. Follow the official Mattermost upgrade documentation to apply the upgrade.
- 4. After upgrade, verify that OAuth login redirect functionality works correctly by testing with a legitimate OAuth provider.
- 5. Confirm the redirect URL validation is properly enforced by attempting a test redirect to an external domain (should be blocked).
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 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 $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-9084 — 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-2025-9084 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