CVE-2026-8435Network attack vector

File-version approval via cross-site requests

Published May 21, 2026 · Updated May 21, 2026

CSRF in Concrete CMS 9.0 through 9.5.0 allows remote attackers to approve file versions through a victim's browser. The affected Backend\File::approveVersion action processes a state-changing request, but Concrete CMS has not published the missing request-validation detail. Exploitation requires passive interaction by a user whose authenticated session can approve the targeted version, and the reported impact is limited to file-version integrity.

CVSS severity2.3
Low
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSRF in Concrete CMS 9.0 through 9.5.0 allows remote attackers to approve file versions through a victim's browser. The affected Backend\File::approveVersion action processes a state-changing request, but Concrete CMS has not published the missing request-validation detail. Exploitation requires passive interaction by a user whose authenticated session can approve the targeted version, and the reported impact is limited to file-version integrity.

The record

CVE
CVE-2026-8435
Published
May 21, 2026
Updated
May 21, 2026
Vendor
Concrete CMS
Product
Concrete CMS
Classifications
CWE-1275, CWE-352
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 21, 2026CVE publishedPublication date reported by the CVE source.
  2. May 21, 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 privilegesunauthenticated

What is affected?

Concrete CMS · Concrete CMSversion=9.0 <=9.5.0

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
2.3ConcreteCMSCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA: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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1275Sensitive Cookie with Improper SameSite Attribute
CWE-352Cross-Site Request Forgery (CSRF)

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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