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WordPressCMS

CVE-2021-39201

MEDIUM · 5.4 CVSS v3.1 Published 2021-09-09
Fix available
A fix is available. Upgrade to 5.8 or later.
See remediation →
58/100
Remediation priority · Elevated
Remotely reachable

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. ### Impact The issue allows an authenticated but low-privileged user (like contributor/author) to execute XSS in the editor. This bypasses the restrictions imposed on users who do not have the permission to post `unfiltered_html`. ### Patches This has been patched in WordPress 5.8, and will be pushed to older versions via minor releases (automatic updates). It's strongly recommended that you keep auto-updates enabled to receive the fix. ### References https://wordpress.org/news/category/releases/ https://hackerone.com/reports/1142140 ### For more information If you have any questions or comments about this advisory: * Open an issue in [HackerOne](https://hackerone.com/wordpress)

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

Authenticated low-privilege users (contributor/author) can execute XSS in the WordPress editor by bypassing the unfiltered_html permission restrictions that normally block script injection for these roles.

MitigationUpdate to WordPress 5.8 or later to receive the patch; ensure automatic minor updates are enabled for future security releases.

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:>= 5.0, < 5.8
Debian LinuxOperating system
Affected:= 10.0= 11.0

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
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/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
    Navigate to Dashboard > About or check the version constant in /wp-includes/version.php
    Affected if Version is 5.0 or higher but lower than 5.8
  2. Verify contributor or author roles exist
    Go to Users > All Users in the admin panel and check for users with Contributor or Author roles
    Affected if At least one user has Contributor or Author role assigned
  3. Confirm posting access for low-privilege roles
    Attempt to create a new post as a Contributor or Author user, or check role capabilities in Users > Roles
    Affected if Contributor or Author users can create or edit posts through the WordPress editor
  4. Check if unfiltered_html is blocked for these roles
    Review role capabilities under Users > User Role Editor or inspect if these roles lack the unfiltered_html capability
    Affected if Roles lack unfiltered_html but still have post editor access (indicates the bypass vulnerability could apply)
  5. Confirm Debian package version if using system package
    Run 'dpkg -l | grep wordpress' or 'apt show wordpress' on the Debian host
    Affected if Installed package version corresponds to WordPress < 5.8 as listed in Debian 10.0 or 11.0

Your environment is affected if WordPress version is 5.0 through 5.7.x AND Contributor or Author user roles exist with access to the post editor.

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
Upgrade available Upgrade to 5.8 or later
Fixed in 5.8
Interim mitigation

Update to WordPress 5.8 or later to receive the patch; ensure automatic minor updates are enabled for future security releases.

Recommended fix High confidence

WordPress 5.8 or later

  1. 1. Backup your WordPress database and files before proceeding with any updates
  2. 2. Ensure automatic updates are enabled in WordPress (add 'AUTOMATIC_UPDATER_DISABLED false' to wp-config.php if needed)
  3. 3. Update WordPress to version 5.8 or later to receive the security patch
  4. 4. Alternatively, manually download WordPress 5.8+ from wordpress.org and update via wp-admin/update-core.php or FTP
  5. 5. Verify the update was successful by checking the WordPress version in Dashboard > Updates or wp-admin/about.php
  6. 6. Test that low-privileged users (contributor/author roles) can no longer inject XSS in the editor
Caveat Review plugin/theme compatibility before upgrading, as some older plugins/themes may not be compatible with WordPress 5.8

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

Fix this in WordPress Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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-2021-39201 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