CVE-2026-27591
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 · uneditedWinter is a free, open-source content management system (CMS) based on the Laravel PHP framework. Prior to 1.0.477, 1.1.12, and 1.2.12, Winter CMS allowed authenticated backend users to escalate their accounts level of access to the system by modifying the roles / permissions assigned to their account through specially crafted requests to the backend while logged in. To actively exploit this security issue, an attacker would need access to the Backend with a user account with any level of access. This vulnerability is fixed in 1.0.477, 1.1.12, and 1.2.12.
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 · high confidenceWinter CMS prior to 1.0.477, 1.1.12, and 1.2.12 contains an insecure direct object reference or missing authorization check allowing any authenticated backend user to modify their own account's roles and permissions through specially crafted API requests, effectively escalating their privileges to administrative levels.
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< 1.0.477>= 1.1.0, < 1.1.12>= 1.2.0, < 1.2.12CVSS 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
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/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 checksWork through these to decide whether this CVE applies to you.
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Determine installed Winter CMS versionLocate the Winter CMS installation directory and check the version file (composer.json or version.php in the core directory). Compare the version number against the affected ranges: < 1.0.477, >= 1.1.0 and < 1.1.12, >= 1.2.0 and < 1.2.12.Affected if The installed version falls within any of the affected version ranges.
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Identify backend user account rolesQuery the backend_users and backend_user_roles database tables (or use the Winter CMS admin panel) to list all backend users and their assigned roles. Note which users have administrative roles versus standard roles.Affected if Any non-administrative backend user account has been assigned elevated roles or permissions that were not intentionally granted through proper admin channels.
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Review API access logs for role modification endpointsExamine server access logs and any Winter CMS API logs for POST/PUT requests to endpoints related to user roles or permissions (such as /api/backend/users/{id}/roles or /api/backend/roles). Look for requests originating from non-admin user accounts.Affected if Non-administrative backend users have made API requests to modify roles or permissions.
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Check for unexpected permission changesInspect the backend_user_role_assignments table or equivalent for any recent changes to role assignments that were not performed by an administrator through the official admin panel.Affected if Role assignments exist that were not created by an administrator via the standard admin interface.
A user is affected if their Winter CMS installation version is below the patched releases AND any backend user account has elevated roles/permissions that were assigned through API requests rather than through proper admin authorization.
Generated from the published advisory. Verify against your own configuration.
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.
dbcve · scoped1.0.4771.1.121.2.12
Upgrade Winter CMS to version 1.0.477, 1.1.12, 1.2.12 or later. If immediate patching is not possible, audit backend user accounts and implement temporary access controls on the roles/permissions endpoints.
Upgrade to 1.0.477 (for 1.0.x branch), 1.1.12 (for 1.1.x branch), or 1.2.12 (for 1.2.x branch)
- 1. Backup your Winter CMS installation and database before proceeding
- 2. Identify your current Winter CMS version by checking the version file or admin panel
- 3. For Winter CMS 1.0.x versions: Upgrade to version 1.0.477
- 4. For Winter CMS 1.1.x versions: Upgrade to version 1.1.12
- 5. For Winter CMS 1.2.x versions: Upgrade to version 1.2.12
- 6. Use your preferred method (Composer or Winter CMS updater) to perform the upgrade
- 7. Clear any cached configurations after upgrade: php artisan cache:clear
- 8. Review backend user accounts and their assigned roles/permissions to detect any unauthorized modifications
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,936.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-27591 — 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 sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-27591 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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