OctoberApplication · Octobercms

CVE-2017-16941

HIGH · 8.8 CVSS v3.0 Published 2017-11-25
Fix available
A fix is available. Upgrade to after 1.0.428 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
October CMS through 1.0.428 does not prevent use of .htaccess in themes, which allows remote authenticated users to execute arbitrary PHP code by downloading a theme ZIP archive from /backend/cms/themes, and then uploading and importing a modified archive with two new files: a .php file and a .htaccess file. NOTE: the vendor says "I don't think [an attacker able to login to the system under an account that has access to manage/upload themes] is a threat model that we need to be considering.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

October CMS through 1.0.428 fails to validate or restrict the contents of uploaded theme archives, allowing authenticated users with theme management permissions to include .htaccess files alongside executable PHP files. When the theme is imported, the .htaccess can be configured to serve PHP files as executable code, achieving arbitrary code execution.

MitigationRestrict theme management permissions to highly trusted administrators only; implement server-side validation to reject theme archives containing .htaccess files during upload/import; upgrade to a patched version if available.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
OctoberApplication
Affected:<= 1.0.428

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed October CMS version
    Locate the version file or admin dashboard 'System > Updates' panel to determine if the version is 1.0.428 or lower
    Affected if Version is 1.0.428 or below
  2. Review theme management permissions
    Navigate to Settings > Users > Permissions and identify which user roles have 'theme management' or 'manage themes' capabilities enabled
    Affected if Any user role other than full administrators has theme management permissions granted
  3. Inspect theme directory for .htaccess files
    Use file system access to list all .htaccess files within the /themes directory and any installed theme subdirectories
    Affected if Any .htaccess files exist in theme directories that contain directives to execute PHP files (such as SetHandler or AddType for PHP execution)
  4. Examine theme archives for embedded .htaccess
    If recent theme imports occurred, extract and inspect any downloaded or uploaded theme .zip archives for the presence of .htaccess files before import
    Affected if Theme archives contain .htaccess files alongside PHP files

A user is affected if running October CMS version 1.0.428 or lower AND has theme management permissions enabled for non-administrator accounts, with potential compromise evidenced by suspicious .htaccess or PHP files in theme directories.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Upgrade available Upgrade to a release after 1.0.428
Interim mitigation

Restrict theme management permissions to highly trusted administrators only; implement server-side validation to reject theme archives containing .htaccess files during upload/import; upgrade to a patched version if available.

Fix this in October Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2017-16941 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-16941 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data