CVE-2024-40886
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 9.9.x <= 9.9.1, 9.5.x <= 9.5.7, 9.10.x <= 9.10.0, 9.8.x <= 9.8.2 fail to sanitize user inputs in the frontend that are used for redirection which allows for a one-click client-side path traversal that is leading to CSRF in User Management page of the system console.
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 fails to sanitize user-supplied inputs used for redirection in the frontend, enabling a client-side path traversal attack. This vulnerability can be exploited in a single click to perform Cross-Site Request Forgery (CSRF) attacks against the User Management page in the system console.
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>= 9.5.0, < 9.5.8>= 9.8.0, < 9.8.3>= 9.9.0, < 9.9.2>= 9.10.0, < 9.10.1CVSS 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
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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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Check installed Mattermost versionAccess the Mattermost System Console and navigate to About > Mattermost, or use the mmctl CLI tool with 'mmctl version' command, or check the version from the about page in the main UIAffected if version falls within >= 9.5.0, < 9.5.8 OR >= 9.8.0, < 9.8.3 OR >= 9.9.0, < 9.9.2 OR >= 9.10.0, < 9.10.1
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Confirm authenticated access to web interfaceVerify that users can log in via the Mattermost web UI and access the frontend applicationAffected if web interface is accessible and users have valid credentials to authenticate
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Verify System Console access existsLog in as a user with System Admin privileges and confirm access to the System Console at /admin_console pathAffected if authenticated user has System Admin role granting access to User Management in System Console
User is affected if Mattermost version is within the affected ranges AND the web interface with System Console access is available to authenticated users.
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 · scoped9.5.89.8.39.9.2
Upgrade Mattermost to versions 9.9.2, 9.5.8, 9.10.1, or 9.8.3 or later. As a temporary measure, users should avoid clicking untrusted links that could manipulate the redirection parameters.
Upgrade to the latest patch version in your current branch: 9.5.8, 9.8.3, 9.9.2, or 9.10.1 (or later)
- Identify the currently running Mattermost version from the affected list (9.5.x, 9.8.x, 9.9.x, or 9.10.x)
- Download the corresponding fixed version: 9.5.8 for 9.5.x branches, 9.8.3 for 9.8.x branches, 9.9.2 for 9.9.x branches, or 9.10.1 for 9.10.x branches
- Follow the standard Mattermost upgrade procedure for your deployment method (e.g., mattermostctl upgrade for Docker/Swarm, or package manager for Linux installations)
- After upgrade, verify the Mattermost server is running the patched version in the System Console > About page
- Confirm the CSRF vulnerability is remediated by testing that the User Management page no longer allows one-click path traversal via redirect parameters
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-40886 — 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-2024-40886 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