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CVE-2026-8353

LOW 2.1

Published 2026-05-22 · Last modified 2026-05-22

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. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 2.1 with 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. Thanks Yonatan Drori (Tenzai) for reporting.

NO EXPLOITATION SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.1%chance of exploitation in 30 days · 5th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

2.1CVSS 4.0 · LOW

  • ConfidentialityLow
  • IntegrityLow
  • AvailabilityNone

What an attacker needs

  • Access: Reachable over the network — no local access needed
  • Privileges: Requires an admin / high-privilege account
  • User interaction: No user interaction needed
  • Complexity: No special conditions — reliably repeatable
  • Requirements: Specific conditions must be present

✓ lowers the bar for an attacker · ⚠ raises it

Affected

Vendors Concrete Cms

Products Concrete Cms

Weakness (CWE)

  • CWE-79: Cross-site scripting (XSS)

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

Sources: NVD · CVE.org · EPSS