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CVE-2026-81902— Concrete CMS 9.0.0 to 9.5.2 is vulnerable to CSRF on Orphan Block Cleanup

Quick assessment

Affected
Concrete CMS Concrete CMS
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Concrete CMS 9 至 9.5.2 版本在未对“孤立区块移除”面板操作（removeOrphanedBlocks）验证 CSRF 令牌的情况下，存在漏洞。远程攻击者可构造请求，当该请求被拥有目标页面编辑权限的已认证用户加载时，会删除该页面当前版本中的所有区块；未被别名关联到其他页面或剪贴本条目的区块，还会从全局 Blocks 表及其区块类型数据表中被移除，从而永久性销毁内容。Concrete CMS 安全团队将此漏洞的 CVSS v4.0 评分定为 7.1，其向量为：CVSS:4.0/AV:N/AC:L/

CVSS 7.1 · High
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I. Basic Information for CVE-2026-81902

Vulnerability Information
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Vulnerability Title
Concrete CMS 9.0.0 to 9.5.2 is vulnerable to CSRF on Orphan Block Cleanup
Source: CVE Program / CVE List V5
Vulnerability Description
Concrete CMS 9 through 9.5.2 did not validate a CSRF token in the orphaned block removal panel action (removeOrphanedBlocks). A remote attacker could craft a request that, when loaded by an authenticated user holding edit permission on the target page, deleted every block on that page's current version; blocks not aliased to another page or scrapbook entry were also removed from the global Blocks table and their block-type data table, permanently destroying the content. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.1 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
跨站请求伪造(CSRF)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Concrete CMS Concrete CMS 9.0.0 ~ 9.5.2 -

II. Public POCs for CVE-2026-81902

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III. Intelligence Information for CVE-2026-81902

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Vendor Pages for CVE-2026-81902 (1)

Same Patch Batch · Concrete CMS · 2026-09-14 · 7 CVEs total

CVE-2026-18117 7.3 HIGH Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Stored XSS in Custom Page Alias Name
CVE-2026-81900 7.3 HIGH Concrete CMS before 9.5.3 is vulnerable to Stored XSS in the YouTube block (vWidth/vHeight
CVE-2026-18116 7.3 HIGH Concrete CMS 8.3.0 to 9.5.2 is vulnerable to Stored XSS in Calendar Event Name via Workflo
CVE-2026-81901 7.2 HIGH Concrete CMS 9.2.0 to 9.5.2 is vulnerable to stored XSS due to missing authorization in th
CVE-2026-18119 7.0 HIGH Concrete CMS below 9.5.3 is vulnerable to Stored XSS via unsanitized inline block custom s
CVE-2026-81903 7.0 HIGH Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Stored XSS via Page Container icon

IV. Related Vulnerabilities

Same product: Concrete CMS
Same vendor: Concrete CMS
Same weakness: CWE-352

V. Comments for CVE-2026-81902

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