Core update execution via unvalidated CSRF token
Published May 21, 2026 · Updated May 21, 2026
Cross-site request forgery in Concrete CMS 9.5.0 and earlier allows remote attackers to trigger a core update via a crafted POST. The do_update() controller accepts the submitted version string and starts the update without validating the do_update CSRF token emitted by its view. An authenticated administrator with canUpgrade() must submit the request, and a valid update version must already exist under DIR_CORE_UPDATES.
Summary
What happened
Cross-site request forgery in Concrete CMS 9.5.0 and earlier allows remote attackers to trigger a core update via a crafted POST. The do_update() controller accepts the submitted version string and starts the update without validating the do_update CSRF token emitted by its view. An authenticated administrator with canUpgrade() must submit the request, and a valid update version must already exist under DIR_CORE_UPDATES.
The record
- CVE
- CVE-2026-8428
- Published
- May 21, 2026
- Updated
- May 21, 2026
- Vendor
- Concrete CMS
- Product
- Concrete CMS
- Classifications
- CWE-352, CWE-829, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 21, 2026CVE publishedPublication date reported by the CVE source.
- 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.
- Affected versionversion=5.0 <=9.5.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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