CVE-2026-2735: Alkacon OpenCms · XSS or 'Cross-site Scripting'
Affects Alkacon OpenCmsSource CVE Database V5
Not known to be exploited · CVSS 5.1 Medium.
Data as of 26 Oct 2026, 17:16 UTC
- 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:NExploitation evidence
Disclosed: evidence found.
CVE published 19 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| AlkaconOpenCms | Affected
| Fixed in– |
AI-suggested
- Apply vendor patches promptly once available to address the root cause of improper input validation.
- 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.
- Deploy Content Security Policy (CSP) headers to restrict execution of unauthorized scripts and reduce XSS impact.
- 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'.
- Conduct regular security audits and code reviews focusing on user input handling in OpenCms customizations.
- Educate users and administrators about the risks of XSS and encourage cautious behavior regarding suspicious links or content.
- Monitor logs and user reports for signs of XSS exploitation attempts or unusual activity related to the vulnerable endpoint.
- 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.