Vulnerability Details CVE-2026-8134
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 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.005
EPSS Ranking 67.7%
CVSS Severity
CVSS v3 Score 7.2
References
Products affected by CVE-2026-8134
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cpe:2.3:a:concretecms:concrete_cms:-
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cpe:2.3:a:concretecms:concrete_cms:5.4.1.1
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cpe:2.3:a:concretecms:concrete_cms:5.4.2
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cpe:2.3:a:concretecms:concrete_cms:5.4.2.1
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cpe:2.3:a:concretecms:concrete_cms:5.4.2.2
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cpe:2.3:a:concretecms:concrete_cms:5.6.1
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cpe:2.3:a:concretecms:concrete_cms:5.6.1.1
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cpe:2.3:a:concretecms:concrete_cms:5.6.1.2
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cpe:2.3:a:concretecms:concrete_cms:5.6.2
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cpe:2.3:a:concretecms:concrete_cms:5.6.2.1
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cpe:2.3:a:concretecms:concrete_cms:5.6.3
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cpe:2.3:a:concretecms:concrete_cms:5.6.3.1
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cpe:2.3:a:concretecms:concrete_cms:5.6.3.3
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cpe:2.3:a:concretecms:concrete_cms:5.6.3.4
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cpe:2.3:a:concretecms:concrete_cms:5.6.3.5
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cpe:2.3:a:concretecms:concrete_cms:5.6.4.0
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cpe:2.3:a:concretecms:concrete_cms:5.7.0
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cpe:2.3:a:concretecms:concrete_cms:5.7.0.1
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cpe:2.3:a:concretecms:concrete_cms:5.7.0.3
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cpe:2.3:a:concretecms:concrete_cms:5.7.0.4
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cpe:2.3:a:concretecms:concrete_cms:5.7.1
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cpe:2.3:a:concretecms:concrete_cms:5.7.2
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cpe:2.3:a:concretecms:concrete_cms:5.7.2.1
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cpe:2.3:a:concretecms:concrete_cms:5.7.3
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cpe:2.3:a:concretecms:concrete_cms:5.7.3.1
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cpe:2.3:a:concretecms:concrete_cms:5.7.4
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cpe:2.3:a:concretecms:concrete_cms:5.7.4.1
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cpe:2.3:a:concretecms:concrete_cms:5.7.4.2
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cpe:2.3:a:concretecms:concrete_cms:5.7.5
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.1
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.10
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.11
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.12
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.13
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.2
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.3
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.4
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.5
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.6
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.7
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.8
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cpe:2.3:a:concretecms:concrete_cms:5.7.5.9
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cpe:2.3:a:concretecms:concrete_cms:5.8.1.0
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cpe:2.3:a:concretecms:concrete_cms:5.8.2.0
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cpe:2.3:a:concretecms:concrete_cms:8.0
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cpe:2.3:a:concretecms:concrete_cms:8.0.1
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cpe:2.3:a:concretecms:concrete_cms:8.0.2
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cpe:2.3:a:concretecms:concrete_cms:8.0.3
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cpe:2.3:a:concretecms:concrete_cms:8.1.0
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cpe:2.3:a:concretecms:concrete_cms:8.2.0
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cpe:2.3:a:concretecms:concrete_cms:8.2.1
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cpe:2.3:a:concretecms:concrete_cms:8.3.0
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cpe:2.3:a:concretecms:concrete_cms:8.3.1
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cpe:2.3:a:concretecms:concrete_cms:8.3.2
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cpe:2.3:a:concretecms:concrete_cms:8.4.0
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cpe:2.3:a:concretecms:concrete_cms:8.4.1
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cpe:2.3:a:concretecms:concrete_cms:8.4.2
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cpe:2.3:a:concretecms:concrete_cms:8.4.3
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cpe:2.3:a:concretecms:concrete_cms:8.4.4
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cpe:2.3:a:concretecms:concrete_cms:8.4.5
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cpe:2.3:a:concretecms:concrete_cms:8.5.0
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cpe:2.3:a:concretecms:concrete_cms:8.5.1
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cpe:2.3:a:concretecms:concrete_cms:8.5.10
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cpe:2.3:a:concretecms:concrete_cms:8.5.11
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cpe:2.3:a:concretecms:concrete_cms:8.5.12
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cpe:2.3:a:concretecms:concrete_cms:8.5.13
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cpe:2.3:a:concretecms:concrete_cms:8.5.14
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cpe:2.3:a:concretecms:concrete_cms:8.5.15
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cpe:2.3:a:concretecms:concrete_cms:8.5.16
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cpe:2.3:a:concretecms:concrete_cms:8.5.17
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cpe:2.3:a:concretecms:concrete_cms:8.5.18
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cpe:2.3:a:concretecms:concrete_cms:8.5.19
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cpe:2.3:a:concretecms:concrete_cms:8.5.2
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cpe:2.3:a:concretecms:concrete_cms:8.5.20
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cpe:2.3:a:concretecms:concrete_cms:8.5.21
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cpe:2.3:a:concretecms:concrete_cms:8.5.3
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cpe:2.3:a:concretecms:concrete_cms:8.5.4
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cpe:2.3:a:concretecms:concrete_cms:8.5.5
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cpe:2.3:a:concretecms:concrete_cms:8.5.6
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cpe:2.3:a:concretecms:concrete_cms:8.5.7
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cpe:2.3:a:concretecms:concrete_cms:8.5.8
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cpe:2.3:a:concretecms:concrete_cms:8.5.9
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cpe:2.3:a:concretecms:concrete_cms:9.0
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cpe:2.3:a:concretecms:concrete_cms:9.0.0
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cpe:2.3:a:concretecms:concrete_cms:9.0.1
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cpe:2.3:a:concretecms:concrete_cms:9.0.2
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cpe:2.3:a:concretecms:concrete_cms:9.1.0
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cpe:2.3:a:concretecms:concrete_cms:9.1.1
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cpe:2.3:a:concretecms:concrete_cms:9.1.2
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cpe:2.3:a:concretecms:concrete_cms:9.1.3
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cpe:2.3:a:concretecms:concrete_cms:9.2.0
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cpe:2.3:a:concretecms:concrete_cms:9.2.1
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cpe:2.3:a:concretecms:concrete_cms:9.2.2
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cpe:2.3:a:concretecms:concrete_cms:9.2.3
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cpe:2.3:a:concretecms:concrete_cms:9.2.4
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cpe:2.3:a:concretecms:concrete_cms:9.2.5
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cpe:2.3:a:concretecms:concrete_cms:9.2.6
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cpe:2.3:a:concretecms:concrete_cms:9.2.7
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cpe:2.3:a:concretecms:concrete_cms:9.2.8
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cpe:2.3:a:concretecms:concrete_cms:9.2.9
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cpe:2.3:a:concretecms:concrete_cms:9.3.0
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cpe:2.3:a:concretecms:concrete_cms:9.3.1
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cpe:2.3:a:concretecms:concrete_cms:9.3.2
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cpe:2.3:a:concretecms:concrete_cms:9.3.3
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cpe:2.3:a:concretecms:concrete_cms:9.3.4
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cpe:2.3:a:concretecms:concrete_cms:9.3.5
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cpe:2.3:a:concretecms:concrete_cms:9.3.6
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cpe:2.3:a:concretecms:concrete_cms:9.3.7
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cpe:2.3:a:concretecms:concrete_cms:9.3.8
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cpe:2.3:a:concretecms:concrete_cms:9.3.9
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cpe:2.3:a:concretecms:concrete_cms:9.4.0
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cpe:2.3:a:concretecms:concrete_cms:9.4.1
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cpe:2.3:a:concretecms:concrete_cms:9.4.2
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cpe:2.3:a:concretecms:concrete_cms:9.4.3
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cpe:2.3:a:concretecms:concrete_cms:9.4.4
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cpe:2.3:a:concretecms:concrete_cms:9.4.5
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cpe:2.3:a:concretecms:concrete_cms:9.4.6
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cpe:2.3:a:concretecms:concrete_cms:9.4.7
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cpe:2.3:a:concretecms:concrete_cms:9.4.8
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cpe:2.3:a:concretecms:concrete_cms:9.5.0