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CVE-2026-18424— Concrete CMS 9.0.0 to 9.5.2 is vulnerable to SSRF protection bypass in remote file import when multiple URLs share a host but use different ports

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 9.0.0 至 9.5.2 版本存在服务器端请求伪造（SSRF）漏洞，可通过跨端口复用已通过验证的主机 DNS 固定值，从而引发远程文件导入时的安全隐患。当多个远程 URL 共享相同的主机名时，系统仅保留并重用第一个通过验证的 用于该主机后续所有 URL。因此，拥有文件导入权限的低权限已认证用户可以提供一个“DNS 重绑定”主机：该主机在验证阶段解析为公网地址，而在未固定的下载阶段解析为私有地址或回环地址，导致服务器会请求仅内部可访问的资源，例如回环服务、内部管理面板或云元数据端点，并将响

CVSS 2.1 · Low

Affected Version Matrix 1

VendorProduct Version RangeStatus
Concrete CMS Concrete CMS 9.0.0≤ 9.5.2 affected
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I. Basic Information for CVE-2026-18424

Vulnerability Information
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Vulnerability Title
Concrete CMS 9.0.0 to 9.5.2 is vulnerable to SSRF protection bypass in remote file import when multiple URLs share a host but use different ports
Source: CVE Program / CVE List V5
Vulnerability Description
Concrete CMS 9.0.0 to 9.5.2 is vulnerable to Server-Side Request Forgery iremote file import via cross-port reuse of a host's validated DNS pin. When multiple remote URLs share the same host, only the first `ValidatedRemoteUrl` is retained and reused for every later URL with that host. A low-privileged authenticated user permitted to import files could therefore supply a DNS-rebinding host that resolved to a public address during validation and to a private or loopback address during the unpinned download, causing the server to fetch internal-only resources such as loopback services, internal admin panels, or cloud metadata endpoints and to save the responses into the file manager. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N. Thanks Ahmad Wicaksono (sonix03) for reporting.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
服务端请求伪造(SSRF)
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-2026-18424

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III. Intelligence Information for CVE-2026-18424

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Vendor Pages for CVE-2026-18424 (1)

Same Patch Batch · Concrete CMS · 2026-09-15 · 31 CVEs total

CVE-2026-18110 8.7 HIGH Concrete CMS 9.0.0 through 9.5.2 is vulnerable to missing authorization in the user select
CVE-2026-81894 8.5 HIGH Concrete CMS 9.5.2 and below is vulnerable to Stored DOM-based Cross-site Scripting (XSS)
CVE-2026-18111 8.5 HIGH Concrete CMS below 9.5.4 allows privilege escalation because adding users and assigning gr
CVE-2026-81895 8.5 HIGH Concrete CMS 9.5.2 and below is vulnerable to Stored SQL Injection in Concrete CMS Documen
CVE-2026-81896 8.4 HIGH Concrete CMS below version 9.5.3 is vulnerable to Stored XSS in Concrete CMS Form Submissi
CVE-2026-81897 7.7 HIGH Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via Express form Text control
CVE-2026-81898 7.5 HIGH Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via country-less Address att
CVE-2026-18113 7.5 HIGH Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS in the Top Navigation Bar Block via
CVE-2026-18115 7.4 HIGH In Concrete CMS 9.2.0 to 9.5.2, Missing Authorization in REST API Users update() and chang
CVE-2026-81899 7.3 HIGH Concrete CMS 9.0 to 9.5.2 is vulnerable to Stored XSS via group folder name on the Members
CVE-2026-68533 2.3 LOW Missing Authorization in Concrete CMS versions below 9.5.3 Conversation File Upload Allows
CVE-2026-81921 2.3 LOW In Concrete CMS 8.5.3 to 9,5,2, OAuth 2.0 Refresh-Token Grant Bypasses Account Status
CVE-2026-81920 2.3 LOW Concrete CMS below 9.5.3 is vulnerable to Cross-Site Request Forgery (CSRF) in Dashboard S
CVE-2026-68532 2.3 LOW Concrete CMS 9.0.0 to 9.5.2 is vunerable to CSRF in Concrete CMS Group Type Deletion Dashb
CVE-2026-68534 2.3 LOW Concrete CMS below 9.5.2 is vulnerable to Stored XSS via unescaped Express entry labels in
CVE-2026-81919 2.3 LOW Concrete CMS below 9.5.3 is vulnerable to Cross-Site Request Forgery (CSRF) in Block Arran
CVE-2026-81922 2.1 LOW "In Concrete CMS below 9.5.3, there is Missing authorization in the sitemap page reorder a
CVE-2026-81925 2.1 LOW Concrete CMS below 9.5.3 is vulnerable to Reflected Cross-Site Scripting (XSS) via Convers
CVE-2026-18425 2.1 LOW IDOR in Concrete CMS 9.0.0 through 9.5.2 dashboard sitemap reorder (SitemapUpdate::updateD
CVE-2026-18422 2.1 LOW Concrete CMS below 9.5.3 Multilingual Page Assign Action Lacks Destination Authorization a

Showing top 20 of 31 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Concrete CMS
Same vendor: Concrete CMS
Same weakness: CWE-918

V. Comments for CVE-2026-18424

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