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VulnerabilityPublished Updated

CVE-2026-2735: Alkacon OpenCms · XSS or 'Cross-site Scripting'

Affects Alkacon OpenCmsSource CVE Database V5

0

Not known to be exploited · CVSS 5.1 Medium.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 4.0 base score
5.1Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 19 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
AlkaconOpenCmsAffected
  • =18.0
Fixed in–

AI-suggested

  1. Apply vendor patches promptly once available to address the root cause of improper input validation.
  2. Until patches are released, implement strict input validation and sanitization on the 'text' parameter at the application or web server level to block malicious scripts.
  3. Deploy Content Security Policy (CSP) headers to restrict execution of unauthorized scripts and reduce XSS impact.
  4. Use web application firewalls (WAFs) with rules targeting common XSS payloads and specifically monitor POST requests to '/blog/new-article/org.opencms.ugc.CmsUgcEditService.gwt'.
  5. Conduct regular security audits and code reviews focusing on user input handling in OpenCms customizations.
  6. Educate users and administrators about the risks of XSS and encourage cautious behavior regarding suspicious links or content.
  7. Monitor logs and user reports for signs of XSS exploitation attempts or unusual activity related to the vulnerable endpoint.
  8. Consider isolating or restricting access to the vulnerable service if feasible until a permanent fix is applied. These measures collectively reduce the likelihood and impact of exploitation beyond generic advice.

Description

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.

References

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