CVE-2025-40631
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 · uneditedHTTP host header injection vulnerability in Icewarp Mail Server affecting version 11.4.0. By modifying the Host header and adding a payload, arbitrary JavaScript code can be executed on page load. The user must interact with a malicious link to be redirected.
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 confidenceHTTP host header injection vulnerability in Icewarp Mail Server 11.4.0 allows attackers to inject arbitrary JavaScript by modifying the Host header with a malicious payload. When users interact with crafted links, the injected script executes in their browser context, enabling reflected XSS attacks.
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= 11.4.0CVSS 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
- 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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Identify Icewarp Mail Server installationCheck for Icewarp installation directories, services, or running processes. Common paths: C:\Program Files\Icewarp\ or /var/www/icewarp/. On Windows, check Services for 'Icewarp' service. On Linux, run 'ps aux | grep icewarp' or check /etc/init.d/icewarp.Affected if Icewarp Mail Server is not installed or is not the affected version (11.4.0)
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Determine installed Icewarp versionCheck version information via the admin web interface (usually at /admin or /webmail), check registry (Windows: HKLM\Software\Icewarp\Version), or examine installed package information. Compare against 11.4.0.Affected if Version is exactly 11.4.0, indicating the specific affected release
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Verify web interface is accessibleConfirm the Icewarp web client or admin panel is reachable over HTTP/HTTPS. Test accessing the login page via browser or curl -I http(s)://<your-server>/. The vulnerability requires the web server component to process Host headers.Affected if Web interface is exposed and processes incoming HTTP requests
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Test for Host header reflectionSend an HTTP request with a manipulated Host header containing a test payload, e.g., 'Host: test.example.com<script>alert(1)</script>'. Examine the response body to see if the Host value or any derivative is reflected without sanitization. Use curl: curl -H 'Host: test.example.com<svg onload=alert(1)>' http://<server-ip>/Affected if The Host header value is reflected unescaped in any response content (login page, error messages, redirects)
A user is affected if Icewarp Mail Server version 11.4.0 is running with its web interface exposed, and the Host header is reflected in responses without sanitization, enabling reflected XSS via malicious Host headers.
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 dataUpgrade to the patched version of Icewarp Mail Server or implement host header validation at the reverse proxy/web server level to reject unexpected host values.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-40631 — 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-2025-40631 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