🛡️ CVE-2026-26067 — system

🟡 CVSS 4.9 — Medium ✅ No Known Exploit CWE-184 NVD
4.9
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

October CMS has Safe Mode Bypass via CSS Preprocessor Compilers

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)

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs administrative privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

Affected software

CVE-2026-26067 is recorded against 2 packages.

  • october/system (from 4.0.0 up to 4.1.10)
  • unknown

Timeline and source

Published on 21 April 2026 and last revised on 5 May 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
nvd.nist.gov (Advisory)
github.com (Package)

Details

Severity Medium
CVSS Score 4.9
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
CWE CWE-184
Public Exploit ✅ No
Source NVD
Published 2026-04-21
Updated 2026-08-12
Modified 2026-05-05
Fix URL N/A

Affected Packages

Software From version Fixed in
october/system 4.0.0 4.1.10
unknown — —

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