CVE-2026-23704
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 · uneditedA non-administrative user can upload malicious files. When an administrator or the product accesses that file, an arbitrary script may be executed on the administrator's browser. Note that Movable Type 7 series and 8.4 series, which are End-of-Life (EOL), are affected by the vulnerability as well.
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 confidenceA stored XSS vulnerability exists in Movable Type where low-privileged users can upload files containing malicious scripts. When an administrator accesses these files through the product interface, the embedded JavaScript executes in the administrator's browser session.
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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
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 Movable Type installation and versionLocate the Movable Type installation directory and check for version indicators such as a VERSION file, mt-config.cgi configuration, or the MT version displayed in the admin interface footer. Compare the found version against the affected ranges for this CVE.Affected if The installed version falls within the vulnerable version range for CVE-2026-23704.
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Identify if file upload functionality is enabledExamine the Movable Type system configuration (mt-config.cgi) or blog/website settings for upload-related parameters such as UploadPermitted, CGIPath with upload capabilities, or upload-enabled directories. Look for AllowFileUpload or similar configuration directives.Affected if File upload functionality is enabled in the system configuration.
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Check user role permissions for upload accessAccess the Movable Type admin panel and navigate to the user/role management section. Review which user roles or permission sets have upload or asset management capabilities. Specifically identify if restricted or low-privileged user accounts (such as commenters, minimal-permission authors, or guests) have been granted upload permissions.Affected if Low-privileged user accounts or roles possess upload or asset creation permissions.
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Verify upload directory is web-accessibleLocate the designated upload/assets directory (commonly named 'upload', 'assets', or 'files' within the MT directory structure). Confirm this directory is served by the web server and accessible via HTTP/HTTPS, allowing uploaded files to be retrieved through the browser.Affected if The upload directory is web-accessible and files can be retrieved through the browser.
A user is affected if they run a vulnerable Movable Type version with file upload functionality enabled for low-privileged user accounts, allowing malicious scripts to be stored and executed in an administrator's browser session.
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 dataImplement strict allowlist-based file type validation, sanitize file metadata/contents, rename uploaded files to remove dangerous extensions, and serve uploaded files with proper Content-Disposition headers to prevent script execution.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-23704 — 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-2026-23704 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