CVE-2025-12154
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 · uneditedThe Auto Thumbnailer plugin for WordPress is vulnerable to arbitrary file uploads due to missing file type validation in the uploadThumb() function in all versions up to, and including, 1.0. This makes it possible for authenticated attackers, with Contributor-level access and above, to upload arbitrary files on the affected site's server which may make remote code execution possible.
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 confidenceThe Auto Thumbnailer WordPress plugin lacks file type validation in its uploadThumb() function, allowing authenticated users with Contributor-level access or higher to upload arbitrary files to the server. This arbitrary file upload vulnerability can be chained to achieve remote code execution.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
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:3.1/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 checksWork through these to decide whether this CVE applies to you.
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Confirm Auto Thumbnailer plugin is installedNavigate to WordPress admin dashboard > Plugins > Installed Plugins and look for 'Auto Thumbnailer' in the list. Note whether it is activated or not.Affected if The plugin is installed and activated in WordPress.
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Identify the installed plugin versionIn the Plugins list, click on 'Auto Thumbnailer' to view the plugin details, or check the plugin files in wp-content/plugins/auto-thumbnailer/ for a version marker in the main PHP file or readme.txt.Affected if Any version of the Auto Thumbnailer plugin is installed (the vulnerability exists in the uploadThumb function across unpatched versions).
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Verify access to uploadThumb functionCheck if the wp-content/plugins/auto-thumbnailer/ directory exists and contains PHP files. The uploadThumb() function is the vulnerable upload handler.Affected if The plugin directory and its uploadThumb function are present on the server.
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Review user role permissionsIn WordPress admin, go to Users > All Users and identify which users have Contributor-level or higher access (Contributor, Author, Editor, Administrator).Affected if There are user accounts with Contributor-level access or higher who can access the plugin functionality.
Your environment is affected if the Auto Thumbnailer plugin is installed and active with Contributor-level or higher user accounts present, as the uploadThumb() function lacks file type validation.
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.
From vendor dataUpgrade to a patched version of the plugin that implements proper file type validation and sanitization in the uploadThumb() function, or disable the plugin until a fix is available.
- Consultation2.0 h
- Implementation3.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-12154 — 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-2025-12154 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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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.
- 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