CVE-2026-8134
Path Traversal in Concretecms Concrete Cms ≤ 9.5.0
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XSummary
CVE-2026-8134 is a critical-severity Relative Path Traversal (CWE-23) vulnerability in Concretecms Concrete Cms. Its CVSS base score is 9.4 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked in the top 49% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-31335
Vulnerability Data
Concrete CMS 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlCustomTemplate field when saving page type composer form layouts. An authenticated rogue administrator with composer form editing rights can exploit this to include arbitrary readable files on…
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the server. Combined with the file uploader's extension-only validation (which permits PHP code in files saved with image extensions like .png), this can result in authenticated remote code execution. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 9.4 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H Thanks Yonatan Drori (Tenzai) for reporting.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V5.3.2V5.1.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and static analysis can discover missing filename restrictions before deployment.
Explicit validation of path inputs stops .. sequences from ever being interpreted by the file system.
Malicious-code protection at entry points blocks dangerous file types from being accepted and executed.
Access enforcement directly blocks unauthorized file reads/writes that result from unresolved .. sequences.
Information-flow rules can be configured to reject traversals that would move data outside an approved directory boundary.
Least privilege reduces the set of reachable files even when a traversal succeeds.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Restricting execution of unauthorized software directly blocks dangerous uploaded files from running.
Secure SDLC practices directly require input validation and path sanitization that prevent relative traversal.
Hardened runtime configuration (e.g., allow_url_include=off) directly blocks RFI even if code is flawed.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development catches path traversal via static/dynamic analysis, but does not itself implement the fix.
Secure development lifecycle mandates input validation and path-handling controls that directly prevent relative path traversal.
Application security requirements explicitly call for controls against path traversal and other injection flaws.
Secure architecture principles include directory isolation and canonicalization, reducing but not eliminating traversal risk.
Secure coding standards require neutralizing path traversal sequences, directly addressing CWE-23.
Information access restriction limits which files can be reached, mitigating impact but not preventing the traversal flaw.