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WordPressCMS

CVE-2021-39203

MEDIUM · 6.5 CVSS v3.1 Published 2021-09-09
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
71/100
Remediation priority · Elevated
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
WordPress is a free and open-source content management system written in PHP and paired with a MySQL or MariaDB database. In affected versions authenticated users who don't have permission to view private post types/data can bypass restrictions in the block editor under certain conditions. This affected WordPress 5.8 beta during the testing period. It's fixed in the final 5.8 release.

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 confidence

In WordPress 5.8 beta, authenticated users lacking permission to view private post types could bypass access restrictions in the block editor (Gutenberg), allowing unauthorized access to private content they should not be able to see.

MitigationUpgrade to WordPress 5.8 or later final release, which contains the fix for this authorization bypass in the block editor.

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
WordPressCMS
Affected:= 5.8

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
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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. Check WordPress version
    In the WordPress admin dashboard, go to Dashboard > Updates or check the site source for the wp_version meta tag. Alternatively, check the version in wp-includes/version.php
    Affected if Version is exactly 5.8 or a beta release of 5.8 (e.g., 5.8-beta1, 5.8-beta2)
  2. Confirm block editor is active
    Navigate to Settings > Writing in WordPress admin and verify that the block editor (Gutenberg) is selected as the default editor, or check if the Gutenberg plugin is active
    Affected if Block editor (Gutenberg) is enabled as the default post editor
  3. Identify private post types
    Review the site's registered custom post types by examining theme or plugin code, or check the wp_posts table where post_status equals 'private'
    Affected if The site uses custom post types with private visibility or has private posts published
  4. Audit user role permissions
    Go to Users > All Users in the admin panel and review which user roles exist. Check if any roles lack the 'read_private_posts' capability but have contributor, author, or editor roles
    Affected if There are authenticated users with limited roles (contributor, author, editor) who should not have access to private content but can access the block editor
  5. Test private content access
    Using a test account with a low-privilege role (e.g., contributor), attempt to create or edit a post via the block editor and observe if private post types appear in queries or autocomplete
    Affected if Users without private post permissions can view or access private content through the block editor interface

A site is affected if running WordPress 5.8 beta with the block editor enabled and having authenticated users with limited permissions who should be restricted from accessing private post types.

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.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to WordPress 5.8 or later final release, which contains the fix for this authorization bypass in the block editor.

Recommended fix High confidence

WordPress 5.8.0 or latest 5.8.x stable release

  1. Ensure you have a complete backup of your WordPress database and files before upgrading
  2. Download WordPress 5.8.0 or the latest 5.8.x stable release from wordpress.org
  3. Upgrade your WordPress installation to the 5.8.x release via your hosting control panel, WP-CLI, or by replacing core files manually
  4. Verify the block editor correctly enforces permissions for private post types post-upgrade
  5. Confirm that users without 'read_private_posts' capability cannot access private content through the block editor
Caveat Minimal risk - this is a patch release fixing a security issue; the final 5.8 release contained only bug fixes and security improvements from the beta

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in WordPress Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
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Scan for this in your stack

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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-2021-39203 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