cvedb.io
CVE-2026-8135
HIGH · CVSS 7.2
EPSS exploitation probability: 0%
Published 2026-05-21T21:16:32.970 · Last modified 2026-06-17T11:03:32.850

Summary

Concrete CMS 9.5.0 and below is vulnerable to Remote Code Execution due to insecure deserialization occurring in the ExpressEntryList block controller. An rogue administrator with privileges to add blocks to an area can bypass the intended protection mechanism (_fromCIF === true), which normally restricts malicious inputs over form POST requests, by leveraging the REST API functionality. Because the REST API parses requests using json_decode(), the string "true" is evaluated as a strict PHP Boolean(true).  This bypass allows the attacker to inject a malicious serialized payload  into the block's filterFields database column. The payload will subsequently be executed when the block's data is viewed or edited by an administrator leading to complete server takeover (RCE).The Concrete CMS sec

Affected products

concretecms — concrete_cms

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.