CVE-2026-8134 Details
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.
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Exploit prediction scoring system (EPSS) score for CVE-2026-8134
EPSS (Exploit Prediction Scoring System): EPSS predicts the likelihood that a vulnerability will be exploited in the wild. A higher percentage means a greater chance of an exploit occurring. The EPSS model produces a probability score between 0 and 1 (0 and 100%).
0.74 Probability of exploitation activity being observed over the next 30 days (50th percentile)
CVSS score for CVE-2026-8134
CVSS (Common Vulnerability Scoring System): An open framework owned and managed by FIRST.Org, Inc. that assigns a numerical score from 0 to 10 to software vulnerabilities to indicate their severity.
7.2 High
Products affected by CVE-2026-8134
ConcreteCMS 5.4.1.1
ConcreteCMS 5.4.2
ConcreteCMS 5.4.2.1
ConcreteCMS 5.4.2.2
ConcreteCMS 5.6.1
DVE Score by Bitsight AI
DVE scores complement traditional static scoring systems like CVSS with Bitsight AI powered real-time threat intelligence and underground cyber criminal activity so that security teams can reduce alert fatigue and focus on vulnerabilities most likely to be exploited.
Low
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CVE-2026-8134 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 5,545 38.43%
DE 1,893 13.12%
JP 1,399 9.70%
GB 1,211 8.39%
NL 689 4.77%
CA 607 4.21%
FR 398 2.76%
PL 394 2.73%
AU 330 2.29%
CH 322 2.23%

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CVE-2026-8134 Industry Footprint

Top 10 Identified Industries

*Service provider organizations (typically Technology and Telecommunications) are disproportionally represented in the results given their upstream ownership of end-user infrastructure. See our FAQs.

Industry* Observations Percentage
Technology 11,280 88.51%
Telecommunications 1,090 8.55%
Education 128 1.00%
Business Services 83 0.65%
Media/Entertainment 56 0.44%
Government/Politics 18 0.14%
Manufacturing 14 0.11%
Energy/Resources 14 0.11%
Healthcare/Wellness 13 0.10%
Transportation 9 0.07%

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