CVE-2026-26067

Description

A server-side information disclosure vulnerability was identified in the handling of CSS preprocessor files. Backend users with Editor permissions could craft `.less`, `.sass`, or `.scss` files that leverage the compiler's import functionality to read arbitrary files from the server. This worked even with `cms.safe_mode` enabled. ### Impact - Potential exposure of sensitive server-side files - Requires authenticated backend access with Editor permissions - Only relevant when `cms.safe_mode` is enabled (otherwise direct PHP injection is already possible) ### Patches The vulnerability has been patched in v3.7.14 and v4.1.10. When `cms.safe_mode` is enabled, `.less`, `.sass`, and `.scss` files can no longer be created, uploaded, or edited across the CMS editor, media manager, and file upload interfaces. All users are encouraged to upgrade to the latest patched version. ### Workarounds If upgrading immediately is not possible: - Set `cms.editable_asset_types` config to `['css', 'js']` to remove preprocessor file types from the editor - Restrict Editor tool access to fully trusted administrators only - Reported by [Chris Alupului](https://github.com/neosprings)

Affected packages (1)

• Packagist/october/systemfrom 0, < 3.7.14

CVSS scores

References (3)

• ADVISORYhttps://nvd.nist.gov/vuln/detail/CVE-2026-26067
• PATCHhttps://github.com/octobercms/october
• WEBhttps://github.com/octobercms/october/security/advisories/GHSA-3888-q23f-x7qh