CVE-2026-54840
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 · uneditedUnauthenticated Broken Access Control in Newsletters <= 4.13 versions.
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 confidenceThis is an Unauthenticated Broken Access Control vulnerability in the Newsletters WordPress plugin (versions 4.13 and below). Attackers can exploit missing or improper authorization checks to access sensitive functionality without any authentication, potentially allowing them to view, modify, or exfiltrate newsletter subscriber data and send unauthorized emails.
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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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 Newsletters plugin is installedIn WordPress admin, go to Plugins > Installed Plugins and look for 'Newsletters' or 'Newsletters Lite' plugin. Alternatively, check the /wp-content/plugins/ directory for folders containing 'newsletter' in the name.Affected if The Newsletters plugin is present on the WordPress site
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Check installed plugin versionIn WordPress admin, click on the plugin name from the Plugins list to view details, or inspect the plugin's main PHP file header for the 'Version' tag. Compare against 4.13 and below.Affected if The installed version is 4.13 or any version number lower than 4.13
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Identify if public-facing subscriber functionality is exposedAccess the frontend of the site and check if subscription forms, newsletter archives, or subscriber management pages are publicly accessible without login. Look for URLs containing /newsletter/, /subscribe/, or similar paths.Affected if Subscriber signup or management pages are accessible without authentication
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Test for unauthenticated access to newsletter featuresSend a direct POST request to common newsletter endpoints (such as subscription handlers or email dispatch routes) without providing any authentication credentials. Check if the request is processed without requiring a logged-in session.Affected if The site processes newsletter requests from unauthenticated users without rejecting them
The site is affected if the Newsletters WordPress plugin versions 4.13 or below is installed AND its newsletter or subscriber management functionality is accessible without any authentication.
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 the Newsletters plugin to the latest version immediately. If an update is unavailable, disable the plugin temporarily and implement Web Application Firewall rules to block suspicious access patterns as a compensating control.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-54840 — 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-2026-54840 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