CVE-2025-5256
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 · uneditedSummaryThis advisory addresses an Open Redirection vulnerability in Mautic's user unlocking endpoint. This vulnerability could be exploited by an attacker to redirect legitimate users to malicious websites, potentially leading to phishing attacks or the delivery of exploit kits. Open Redirection via returnUrl Parameter: An Open Redirection vulnerability exists in the /s/action/unlock/user.user/0 endpoint. The returnUrl parameter, intended for post-action redirection, is not properly validated. This allows an attacker to craft a URL that, when clicked by a user, redirects them to an arbitrary external website controlled by the attacker. MitigationUpdate Mautic to a version that properly validates or sanitizes the returnUrl parameter to ensure that redirects only occur to trusted, internal URLs or explicitly whitelisted domains.
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 confidenceMautic contains an Open Redirection vulnerability in the /s/action/unlock/user.user/0 endpoint where the returnUrl parameter is not validated before use in redirects. An attacker can craft a malicious URL containing an arbitrary external URL in the returnUrl parameter, causing authenticated users to be redirected to attacker-controlled websites for phishing or malware delivery.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/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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Determine installed Mautic versionAccess the Mautic administration dashboard and navigate to Settings > Configuration > System Info, or check the file app/AppConstants.php for the MAUTIC_VERSION constant, or inspect the composer.json file in the Mautic root directoryAffected if The installed version is any version prior to the fix being applied (compare against official Mautic security advisories for CVE-2025-5256)
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Verify the vulnerable endpoint existsCheck if the route /s/action/unlock/user.user/0 is accessible in the Mautic installation by inspecting the routing configuration files in app/config/routes.php or the equivalent YAML configurationAffected if The endpoint exists and is accessible to authenticated users
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Inspect returnUrl parameter handlingLocate the controller handling the /s/action/unlock route (typically in src/Controller/ActionController.php or similar) and examine how the returnUrl query parameter is processed - look for the code that performs the redirect operationAffected if The code performs a redirect using the returnUrl parameter without validating it against a whitelist of allowed domains or checking that it is an internal URL
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Test for open redirect behavior (if safe to do in non-production)With an authenticated session, navigate to a URL such as /s/action/unlock/user.user/0?returnUrl=https://example.com and observe whether the application redirects to the external domain providedAffected if The application redirects to the arbitrary URL specified in the returnUrl parameter without any warning or validation
A user is affected if they are running any Mautic version where the returnUrl parameter in /s/action/unlock/user.user/0 is used in redirects without validation, allowing arbitrary external URL redirection.
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 dataUpdate Mautic to a version that implements proper validation and sanitization of the returnUrl parameter, restricting redirects to trusted internal URLs or an explicit whitelist of allowed domains.
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 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 $2,560.
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Free · runs locallyCheck whether your project pulls in CVE-2025-5256 — 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-2025-5256 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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- Version or environment caveats, and links to real fixes
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