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OpencmsApplication · Alkacon

CVE-2026-2735

MEDIUM · 5.4 CVSS v3.1 Published 2026-02-19
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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 · unedited
Stored Cross-Site Scripting (XSS) in Alkacon's OpenCms v18.0, which occurs when user input is not properly validated when sending a POST request to ‘/blog/new-article/org.opencms.ugc.CmsUgcEditService.gwt’ using the ‘text’ parameter.

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 confidence

Stored Cross-Site Scripting (XSS) vulnerability in Alkacon OpenCms v18.0 where the blog article submission endpoint at '/blog/new-article/org.opencms.ugc.CmsUgcEditService.gwt' fails to sanitize user input in the 'text' parameter, allowing malicious JavaScript to be persisted and executed when other users view the injected content.

MitigationImplement server-side input validation and output encoding for the 'text' parameter in the CmsUgcEditService.gwt endpoint, and consider deploying Content Security Policy headers to mitigate XSS execution.

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
OpencmsApplication
Affected:= 18.0.0

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
Low
User interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/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 checks

Work through these to decide whether this CVE applies to you.

  1. Verify OpenCms version is 18.0.0
    Check the OpenCms version through the admin interface under 'System' > 'Administration' > 'System Information', or inspect the version file in the Alkacon installation directory (typically VERSION.txt or manifest.xml in the WEB-INF/lib/opencms*.jar)
    Affected if The installed version is exactly 18.0.0 (note: only this specific version is affected)
  2. Confirm blog module is installed and enabled
    Navigate to the OpenCms workplace Admin view, expand 'Administration' > 'Module Management', and verify the blog module (org.opencms.ugc or similar user-generated content module) is listed as installed
    Affected if The blog/user-generated content module is installed and active
  3. Check if CmsUgcEditService endpoint is accessible
    Verify the endpoint '/blog/new-article/org.opencms.ugc.CmsUgcEditService.gwt' exists and responds by accessing it via HTTP request or checking the Alkacon deployment configuration
    Affected if The endpoint is accessible and responding to requests
  4. Inspect blog article storage for existing XSS payloads
    Query the OpenCms database or use the admin interface to view stored blog articles in the '/blog/' resource path. Check the 'text' field content for suspicious HTML/JavaScript patterns such as <script>, javascript:, onload=, or other XSS vectors
    Affected if Stored blog articles contain unsanitized user-supplied HTML or JavaScript in the text content
  5. Verify lack of input validation on text parameter
    Submit a test article via the blog submission form with a benign test payload (e.g., <img src=x onerror=alert(1)> in the text field) and verify it is stored and rendered without encoding or sanitization
    Affected if The test payload is rendered as-is without HTML encoding when viewed

You are affected if running OpenCms 18.0.0 with the blog/user-generated content module enabled and the vulnerable endpoint accessible, especially if content from the 'text' parameter is stored and rendered without server-side sanitization.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement server-side input validation and output encoding for the 'text' parameter in the CmsUgcEditService.gwt endpoint, and consider deploying Content Security Policy headers to mitigate XSS execution.

Fix this in Opencms Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-2735 in production — separate from our analysis above.

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