CVE-2026-81910

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Source

https://cve.org/CVERecord?id=CVE-2026-81910

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81910.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-81910

Published

2026-09-11T18:20:25Z

Modified

2026-09-13T03:47:17Z

Severity

5.9 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N CVSS Calculator

Summary

Concrete CMS 9 through 9.5.2 is vulnerable to Server-Side Template Injection (SSTI) in Theme Customizer via Unvalidated Style Values

Details

Concrete CMS 9 through 9.5.2 is vulnerable to Server-Side Template Injection (SSTI) in Theme Customizer via Unvalidated Style Values. Values submitted through the customizer (color channels and other style properties handled by ColorStyle and sibling Style classes such as FontFamilyStyle and ImageStyle) are interpolated into server-compiled LESS source without neutralization of LESS syntax, allowing a user with the Theme Customization permission to inject arbitrary LESS directives. By injecting the @import (inline) directive, an attacker can read arbitrary files on the server and reach internal network resources through PHP stream wrappers. The compiled output, including any disclosed file contents, is written to the site's publicly served CSS cache, exposing database credentials, private keys, and other application secrets, and enabling server-side request forgery. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.9 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

Database specific

{
    "cna_assigner": "ConcreteCMS",
    "cwe_ids": [
        "CWE-1336"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/81xxx/CVE-2026-81910.json"
}

References

Affected packages

Git / github.com/concretecms/concretecms

Affected ranges

Type

GIT

Repo

https://github.com/concretecms/concretecms

Events

Introduced

b3774abddd475b4ba98b637402506f7a5ebd90ea

Last Affected

8fe9708072c3815a5df719b592e4b23b43b4ff7a

Database specific

Show details

{
    "extracted_events": [
        {
            "introduced": "9.0.0"
        },
        {
            "last_affected": "9.5.2"
        }
    ],
    "source": "AFFECTED_FIELD"
}

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-81910.json"