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Low

Concrete CMS is vulnerable to Stored XSS via page name in the Atomik theme

  • Disclosed: 26.05.2026
  • Updated: 11.10.2026 10:22

Concrete CMS version 9.0 to 9.5.0 is vulnerable to Stored XSS via page name in the Atomik theme. A rogue editor can inject arbitrary JavaScript that executes in the context of any authenticated user visiting the affected account pages. This can lead to session hijacking, credential theft, malicious actions performed on behalf of users, and potential privilege escalation. Thanks Yonatan Drori (Tenzai) for reporting.

Affected software

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PlatformPackageVulnerable versionsFixed in
Composer package concrete5/concrete5 >= 9.0.0RC.1, < 9.5.1 9.5.1

References

CVSS score -
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness (CWE)
CWE-79
Platform
Composer
Package
concrete5/concrete5
Disclosed
26.05.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-q9fm-mpg8-8jqm - CC BY 4.0

Vulnerability history: concrete5/concrete5

All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (121) in the archive
Total entries
121
First → latest
10.2021 06.2026
Without a fix
10
Exploited in attacks
0

Severity breakdown

  • Critical 2
  • High 16
  • Medium 65
  • Low 38

Disclosures per year

Severity:
  1. Concrete CMS: PHP Object Injection via unserialize() calls
    High CVE-2026-10721 < 9.5.2 9.5.2
  2. Concrete CMS is vulnerable to PHP Object Injection via unserialize() calls in the Workflow, Form block, and File/Set components
    High CVE-2026-7888 < 9.5.2 9.5.2
  3. Concrete CMS is vulnerable to Stored XSS via page name in the Atomik theme this entry
    Low CVE-2026-8353 >= 9.0.0RC.1, < 9.5.1 9.5.1
  4. Concrete does not validate a CSRF token before processing requests to `/dashboard/extend/update/do_update/<pkgHandle>`
    High CVE-2026-8417 < 9.5.1 9.5.1
  5. Concrete CMS does not validate a CSRF token before processing requests to `/dashboard/extend/update/prepare_remote_upgrade/<remoteMPID>`
    High CVE-2026-8426 < 9.5.1 9.5.1
  6. Concrete CMS contains a CSRF vulnerability
    High CVE-2026-8421 < 9.5.1 9.5.1
  7. Concrete CMS is Vulnerable to Cross-Site Request Forgery
    High CVE-2026-8428 < 9.5.1 9.5.1
  8. Concrete CMS is vulnerable to missing authorization in the bulk_user_assignment.php
    High CVE-2026-8350 < 9.5.1 9.5.1
  9. Concrete CMS has Stored XSS through its height parameter
    High CVE-2026-8203 < 9.5.1 9.5.1
  10. Concrete CMS is Vulnerable to Cross-Site Request Forgery
    High CVE-2026-8140 < 9.5.1 9.5.1
  11. Concrete CMS Vulnerable to Deserialization of Untrusted Data
    High CVE-2026-8135 < 9.5.1 9.5.1
  12. Concrete CMS is vulnerable to Stored XSS via OAuth integration name
    High CVE-2026-8197 < 9.5.1 9.5.1
  13. Concrete CMS Vulnerable to Relative Path Traversal
    Critical · 7.2 CVE-2026-8134 < 9.5.1 9.5.1
  14. Concrete CMS vulnerable to Remote Code Execution by stored PHP object injection
    High CVE-2026-3452 < 9.4.8 9.4.8
  15. Concrete CMS (previously concrete5) is vulnerable to possible auth bypass in the jobs section
    Critical · 9.8 CVE-2023-28473 < 9.2.0 9.2.0
  16. Concrete CMS vulnerable to Cross-site Request Forgery
    High · 8.8 CVE-2022-43693 < 8.5.10, >= 9.0.0RC1, < 9.1.3 8.5.10, 9.1.3
  17. Cross Site Request Forgery in concrete5/concrete5
    High CVE-2021-22954 < 9.0.0 9.0.0
  18. Unrestricted Uploads in Concrete5
    High · 7.2 CVE-2020-11476 < 8.5.3 8.5.3
  19. Server-Side Request Forgery vulnerability in concrete5
    High · 8.2 CVE-2021-22958 < 8.5.5 8.5.5

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