CVE-2026-8353Network attack vector

Stored XSS via unsanitized collection name output

Published May 22, 2026 · Updated May 22, 2026

Stored XSS in the Atomik theme in Concrete CMS 9.0 through 9.5.0 allows remote authenticated users to execute JavaScript via page names. The Atomik theme renders the collection name into affected account pages without output sanitization. Editor-level page-naming privileges and an authenticated visitor to an affected page are required; successful exploitation exposes browser-session data and permits actions with the visitor's CMS privileges.

CVSS severity2.1
Low
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in the Atomik theme in Concrete CMS 9.0 through 9.5.0 allows remote authenticated users to execute JavaScript via page names. The Atomik theme renders the collection name into affected account pages without output sanitization. Editor-level page-naming privileges and an authenticated visitor to an affected page are required; successful exploitation exposes browser-session data and permits actions with the visitor's CMS privileges.

The record

CVE
CVE-2026-8353
Published
May 22, 2026
Updated
May 22, 2026
Vendor
Concrete CMS
Product
Concrete CMS
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. May 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=9.0 <=9.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Concrete CMS · Concrete CMSversion=9.0 <=9.5.0

Published CVSS scores

2.1ConcreteCMSCVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
4.8NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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