Vulnerability-Lookup

CVE-2026-26067 (GCVE-0-2026-26067)

Vulnerability from cvelistv5 – Published: 2026-04-21 16:16 – Updated: 2026-04-21 17:35

Title

October: Safe Mode Bypass via CSS Preprocessor Compilers

Summary

October is a Content Management System (CMS) and web platform. Prior to 3.7.14 and 4.1.10, 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. This vulnerability is fixed in 3.7.14 and 4.1.10.

Severity

4.9 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-21 17:35 UTC

CWE

CWE-863 - Incorrect Authorization
CWE-184 - Incomplete List of Disallowed Inputs

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/octobercms/october/security/ad…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
octobercms	october	Affected: >= 4.0.0, < 4.1.10 Affected: < 3.7.14	guessed

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JSON

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FKIE_CVE-2026-26067

Vulnerability from fkie_nvd - Published: 2026-04-21 17:16 - Updated: 2026-06-17 10:25

Severity

4.9 (Medium) - CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/octobercms/october/security/advisories/GHSA-3888-q23f-x7qh

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "october",
          "vendor": "octobercms",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.0.0, \u003c 4.1.10"
            },
            {
              "status": "affected",
              "version": "\u003c 3.7.14"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
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    {
      "lang": "en",
      "value": "October is a Content Management System (CMS) and web platform. Prior to 3.7.14 and 4.1.10, 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\u0027s import functionality to read arbitrary files from the server. This worked even with cms.safe_mode enabled. This vulnerability is fixed in 3.7.14 and 4.1.10."
    }
  ],
  "id": "CVE-2026-26067",
  "lastModified": "2026-06-17T10:25:40.647",
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          "integrityImpact": "NONE",
          "privilegesRequired": "HIGH",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N",
          "version": "3.1"
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GHSA-3888-Q23F-X7QH

Vulnerability from github – Published: 2026-04-21 16:43 – Updated: 2026-04-24 21:06

Summary

October CMS has Safe Mode Bypass via CSS Preprocessor Compilers

Details

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

Severity

4.9 (Medium)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "october/system"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.7.14"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Packagist",
        "name": "october/system"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.1.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-26067"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-184",
      "CWE-200",
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-21T16:43:49Z",
    "nvd_published_at": "2026-04-21T17:16:24Z",
    "severity": "MODERATE"
  },
  "details": "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\u0027s 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 `[\u0027css\u0027, \u0027js\u0027]` 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)",
  "id": "GHSA-3888-q23f-x7qh",
  "modified": "2026-04-24T21:06:45Z",
  "published": "2026-04-21T16:43:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/octobercms/october/security/advisories/GHSA-3888-q23f-x7qh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26067"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/octobercms/october"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "October CMS has Safe Mode Bypass via CSS Preprocessor Compilers"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-26067 (GCVE-0-2026-26067)

FKIE_CVE-2026-26067

GHSA-3888-Q23F-X7QH

Impact

Patches

Workarounds

Tags

Sightings

Nomenclature