{"id":"GHSA-3888-q23f-x7qh","aliases":["CVE-2026-26067"],"title":"October CMS has Safe Mode Bypass via CSS Preprocessor Compilers","titleSource":"OSV","descriptionSource":"OSV","declaredSeverity":"MODERATE","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.\n\n### Impact\n- Potential exposure of sensitive server-side files\n- Requires authenticated backend access with Editor permissions\n- Only relevant when `cms.safe_mode` is enabled (otherwise direct PHP injection is already possible)\n\n### Patches\nThe 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.\n\n### Workarounds\nIf upgrading immediately is not possible:\n- Set `cms.editable_asset_types` config to `['css', 'js']` to remove preprocessor file types from the editor\n- Restrict Editor tool access to fully trusted administrators only\n\n- Reported by [Chris Alupului](https://github.com/neosprings)","severity":"medium","score":4.9,"published":"2026-04-21T16:43:49.000Z","modified":"2026-05-05T15:59:59.427Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Packagist","name":"october/system","sources":[{"name":"OSV · GHSA-3888-q23f-x7qh","url":"https://osv.dev/vulnerability/GHSA-3888-q23f-x7qh"}],"ranges":[{"events":[{"introduced":"0"},{"fixed":"3.7.14"}],"type":"ECOSYSTEM"}],"versions":["v1.0.319","v1.0.320","v1.0.321","v1.0.322","v1.0.323","v1.0.324","v1.0.325","v1.0.326","v1.0.327","v1.0.328","v1.0.329","v1.0.330","v1.0.331","v1.0.332","v1.0.333","v1.0.334","v1.0.335","v1.0.336","v1.0.337","v1.0.338","v1.0.339","v1.0.340","v1.0.341","v1.0.342","v1.0.343","v1.0.344","v1.0.345","v1.0.346","v1.0.347","v1.0.348","v1.0.349","v1.0.350","v1.0.351","v1.0.352","v1.0.353","v1.0.354","v1.0.355","v1.0.356","v1.0.357","v1.0.358","v1.0.359","v1.0.360","v1.0.361","v1.0.362","v1.0.363","v1.0.364","v1.0.365","v1.0.366","v1.0.367","v1.0.368","v1.0.369","v1.0.370","v1.0.371","v1.0.372","v1.0.373","v1.0.374","v1.0.375","v1.0.376","v1.0.377","v1.0.378","v1.0.379","v1.0.380","v1.0.381","v1.0.382","v1.0.383","v1.0.384","v1.0.385","v1.0.386","v1.0.387","v1.0.388","v1.0.389","v1.0.390","v1.0.391","v1.0.392","v1.0.393","v1.0.394","v1.0.395","v1.0.396","v1.0.397","v1.0.398","v1.0.399","v1.0.400","v1.0.401","v1.0.402","v1.0.403","v1.0.404","v1.0.405","v1.0.406","v1.0.407","v1.0.408","v1.0.409","v1.0.410","v1.0.411","v1.0.412","v1.0.413","v1.0.414","v1.0.415","v1.0.416","v1.0.417","v1.0.418","v1.0.419","v1.0.420","v1.0.421","v1.0.422","v1.0.423","v1.0.424","v1.0.425","v1.0.426","v1.0.427","v1.0.428","v1.0.429","v1.0.430","v1.0.431","v1.0.432","v1.0.433","v1.0.434","v1.0.435","v1.0.436","v1.0.437","v1.0.438","v1.0.439","v1.0.440","v1.0.441","v1.0.442","v1.0.443","v1.0.444","v1.0.445","v1.0.446","v1.0.447","v1.0.448","v1.0.449","v1.0.450","v1.0.451","v1.0.452","v1.0.453","v1.0.454","v1.0.455","v1.0.456","v1.0.457","v1.0.458","v1.0.459","v1.0.460","v1.0.461","v1.0.462","v1.0.463","v1.0.464","v1.0.465","v1.0.466","v1.0.467","v1.0.468","v1.0.469","v1.0.470","v1.0.471","v1.0.472","v1.0.473","v1.0.474","v1.0.475","v1.0.476","v1.1.0","v1.1.1","v1.1.10","v1.1.11","v1.1.12","v1.1.2","v1.1.3","v1.1.4","v1.1.5","v1.1.6","v1.1.9"],"fixed":["3.7.14"]},{"ecosystem":"Packagist","name":"october/system","sources":[{"name":"OSV · GHSA-3888-q23f-x7qh","url":"https://osv.dev/vulnerability/GHSA-3888-q23f-x7qh"}],"ranges":[{"events":[{"introduced":"4.0.0"},{"fixed":"4.1.10"}],"type":"ECOSYSTEM"}],"versions":[],"fixed":["4.1.10"]}],"sourceAffected":[],"references":["https://github.com/octobercms/october/security/advisories/GHSA-3888-q23f-x7qh","https://nvd.nist.gov/vuln/detail/CVE-2026-26067","https://github.com/octobercms/october"],"sources":[{"name":"OSV","id":"GHSA-3888-q23f-x7qh","modified":"2026-05-05T15:59:59.427971Z","url":"https://osv.dev/vulnerability/GHSA-3888-q23f-x7qh"}],"assessments":[{"source":"OSV","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N","score":4.9}],"products":[],"remediation":[],"kev":{"status":"not-listed","checkedAt":"2026-10-28T16:00:31.263Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}