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CVE-2026-8203

HIGHCVSS 7.3/10EPSS 0.12%

Last modified

CVE-2026-8203 is a high-severity vulnerability rated 7.3/10 on the CVSS scale. Concrete CMS 9.5.0 and below has Stored XSS on the height parameter. The controller does not validate or sanitize $height. Any user with editor privileges can inject malicious JavaScript that executes in the context of any visitor's browser, potentially leading to session hijacking, credential theft, or other malicious actions. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Alfin Joseph for reporting.. EPSS estimates a 0.12% chance of exploitation in the next 30 days.

Description

Concrete CMS 9.5.0 and below has Stored XSS on the height parameter. The controller does not validate or sanitize $height. Any user with editor privileges can inject malicious JavaScript that executes in the context of any visitor's browser, potentially leading to session hijacking, credential theft, or other malicious actions. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Alfin Joseph for reporting.

Metrics

CVSS 3.1
5.4/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS 4.0
7.3/10

CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/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:X

EPSS Probability
0.12%

2.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
ConcretecmsConcrete Cms<= 9.5.0

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-8203?
Concrete CMS 9.5.0 and below has Stored XSS on the height parameter. The controller does not validate or sanitize $height. Any user with editor privileges can inject malicious JavaScript that executes in the context of any visitor's browser, potentially leading to session hijacking, credential theft, or other malicious actions. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 7.3 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Alfin Joseph for reporting.
How severe is CVE-2026-8203?
CVE-2026-8203 has a CVSS score of 7.3/10 (HIGH severity). The EPSS model estimates a 0.12% probability of exploitation in the next 30 days.
How do I fix CVE-2026-8203?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-8203?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST