What is CVE-2026-2735?

CVE-2026-2735 is a medium-severity vulnerability in Alkacon Opencms, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-02-19.

How severe is CVE-2026-2735?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Alkacon Opencms

CVE-2026-2735

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-02-19 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (13.3th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.001

Affected products

Alkacon Opencms — versions 18.0.0, 18.0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

www.incibe.es/en/incibe-cert/notices/aviso/multiple-vulnerabilities-alkacons-op… (Third Party Advisory, patch)

Frequently asked questions

What is CVE-2026-2735?: CVE-2026-2735 is a medium-severity vulnerability in Alkacon Opencms, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-02-19.
How severe is CVE-2026-2735?: Medium severity. CVSS v3 base score is 5.4 out of 10.