CVE-2026-18117 Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Stored XSS in Custom Page Alias Name
An editor can inject malicious scripts via page aliases that execute in admin sessions, enabling privilege escalation to administrator.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-18117?
CVE-2026-18117 is a high-severity cross-site scripting vulnerability in Concretecms Concrete Cms, published on 14 Sep 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
Concrete CMS 9.0.0 through 9.5.3 is vulnerable to stored XSS via the custom page alias name (customAliasName) because the Edit Alias dialog applied only trim() to the submitted value and performed no input neutralization. An authenticated user holding canWrite (editor) permission on a page could store a malicious alias name that was later rendered unescaped in the administrative Sitemap panel, where it executed automatically in any administrator or editor session that opened the panel, allowing an editor to escalate to administrator through the victim's active session. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N. Thanks Nguyen Manh Thuan for reporting.
Weakness: CWE-79
Which versions are affected by CVE-2026-18117?
It affects 1 product.
Products include Concretecms Concrete Cms.
How do I fix CVE-2026-18117?
No fix has been published for CVE-2026-18117 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-18117 being exploited?
There is no known exploitation of CVE-2026-18117 in the wild and no public exploit code.
Other vulnerabilities in Concretecms Concrete Cms
- CVE-2023-48648 Concrete CMS allows unauthorized access because directories can be created with insecure permissions
- CVE-2022-21829 Code injection in concrete CMS
- CVE-2021-22958 Server-Side Request Forgery vulnerability in concrete5
- CVE-2021-40098 Path traversal in n/a
- CVE-2026-8134 Concrete CMS Vulnerable to Relative Path Traversal
Sources
Also known as GHSA-rwvw-4pc9-743m.